diff --git a/rezag/aggindexsource.py b/rezag/aggindexsource.py
index 738c781d..02885f58 100644
--- a/rezag/aggindexsource.py
+++ b/rezag/aggindexsource.py
@@ -13,9 +13,10 @@ from pywb.cdx.query import CDXQuery
 
 from heapq import merge
 from collections import deque
+from itertools import chain
 
 from rezag.indexsource import FileIndexSource
-from pywb.utils.wbexception import NotFoundException
+from pywb.utils.wbexception import NotFoundException, WbException
 import six
 import glob
 
@@ -29,13 +30,10 @@ class BaseAggregator(object):
         query = CDXQuery(params)
         self._set_src_params(params)
 
-        try:
-            cdx_iter = self.load_index(query.params)
-        except NotFoundException as nf:
-            cdx_iter = iter([])
+        cdx_iter, errs = self.load_index(query.params)
 
         cdx_iter = process_cdx(cdx_iter, query)
-        return cdx_iter
+        return cdx_iter, dict(errs)
 
     def _set_src_params(self, params):
         src_params = {}
@@ -60,16 +58,23 @@ class BaseAggregator(object):
         params['_all_src_params'] = src_params
 
     def load_child_source_list(self, name, source, params):
-        return list(self.load_child_source(name, source, params))
+        res = self.load_child_source(name, source, params)
+        return list(res[0]), res[1]
 
     def load_child_source(self, name, source, params):
         try:
             _src_params = params['_all_src_params'].get(name)
             params['_src_params'] = _src_params
-            cdx_iter = source.load_index(params)
-        except NotFoundException as nf:
-            print('Not found in ' + name)
+            res = source.load_index(params)
+            if isinstance(res, tuple):
+                cdx_iter, err_list = res
+            else:
+                cdx_iter = res
+                err_list = []
+        except WbException as wbe:
+            #print('Not found in ' + name)
             cdx_iter = iter([])
+            err_list = [(name, repr(wbe))]
 
         def add_name(cdx):
             if cdx.get('source'):
@@ -78,10 +83,13 @@ class BaseAggregator(object):
                 cdx['source'] = name
             return cdx
 
-        return (add_name(cdx) for cdx in cdx_iter)
+        return (add_name(cdx) for cdx in cdx_iter), err_list
 
     def load_index(self, params):
-        iter_list = self._load_all(params)
+        res_list = self._load_all(params)
+
+        iter_list = [res[0] for res in res_list]
+        err_list = chain(*[res[1] for res in res_list])
 
         #optimization: if only a single entry (or empty) just load directly
         if len(iter_list) <= 1:
@@ -89,7 +97,7 @@ class BaseAggregator(object):
         else:
             cdx_iter = merge(*(iter_list))
 
-        return cdx_iter
+        return cdx_iter, err_list
 
     def _on_source_error(self, name):  #pragma: no cover
         pass
@@ -207,6 +215,7 @@ class GeventMixin(object):
             if job.value is not None:
                 results.append(job.value)
             else:
+                results.append((iter([]), [(name, 'timeout')]))
                 self._on_source_error(name)
 
         return results
@@ -247,7 +256,9 @@ class ConcurrentMixin(object):
                 results.append(job.result())
 
             for job in res_not_done:
-                self._on_source_error(jobs[job])
+                name = jobs[job]
+                results.append((iter([]), [(name, 'timeout')]))
+                self._on_source_error(name)
 
         return results
 
diff --git a/rezag/app.py b/rezag/app.py
index bb4b4892..23f20bce 100644
--- a/rezag/app.py
+++ b/rezag/app.py
@@ -2,25 +2,49 @@ from rezag.inputrequest import DirectWSGIInputRequest, POSTInputRequest
 from bottle import route, request, response, default_app, abort
 import bottle
 
-from pywb.utils.wbexception import WbException
-
 import traceback
 import json
 
+JSON_CT = 'application/json; charset=utf-8'
+
 def err_handler(exc):
     response.status = exc.status_code
-    response.content_type = 'application/json'
-    return json.dumps({'message': exc.body})
+    response.content_type = JSON_CT
+    err_msg = json.dumps({'message': exc.body})
+    response.headers['ResErrors'] = err_msg
+    return err_msg
 
 
 def wrap_error(func):
     def wrap_func(*args, **kwargs):
         try:
-            return func(*args, **kwargs)
-        except WbException as exc:
-            if bottle.debug:
-                traceback.print_exc()
-            abort(exc.status(), exc.msg)
+            res, errs = func(*args, **kwargs)
+
+            if res:
+                if errs:
+                    response.headers['ResErrors'] = json.dumps(errs)
+                return res
+
+            last_exc = errs.pop('last_exc', None)
+            if last_exc:
+                if bottle.debug:
+                    traceback.print_exc()
+
+                response.status = last_exc.status()
+                message = last_exc.msg
+            else:
+                response.status = 404
+                message = 'No Resource Found'
+
+            response.content_type = JSON_CT
+            res = {'message': message}
+            if errs:
+                res['errors'] = errs
+
+            err_msg = json.dumps(res)
+            response.headers['ResErrors'] = err_msg
+            return err_msg
+
         except Exception as e:
             if bottle.debug:
                 traceback.print_exc()
@@ -32,35 +56,33 @@ def wrap_error(func):
 route_dict = {}
 
 def add_route(path, handler):
-    @route(path, 'ANY')
+    @route([path, path + '/<mode:path>'], 'ANY')
     @wrap_error
-    def direct_input_request():
+    def direct_input_request(mode=''):
         params = dict(request.query)
+        params['mode'] = mode
         params['_input_req'] = DirectWSGIInputRequest(request.environ)
         return handler(params)
 
-    @route(path + '/postreq', 'POST')
+    @route([path + '/postreq', path + '/<mode:path>/postreq'], 'POST')
     @wrap_error
-    def post_fullrequest():
+    def post_fullrequest(mode=''):
         params = dict(request.query)
+        params['mode'] = mode
         params['_input_req'] = POSTInputRequest(request.environ)
         return handler(params)
 
     global route_dict
-    handler_dict = {'handler': handler.get_supported_modes()}
+    handler_dict = handler.get_supported_modes()
     route_dict[path] = handler_dict
     route_dict[path + '/postreq'] = handler_dict
 
+
 @route('/')
 def list_routes():
     return route_dict
 
 
-
-
-
-
-
 application = default_app()
 application.default_error_handler = err_handler
 
diff --git a/rezag/handlers.py b/rezag/handlers.py
index a2a7fcd7..fdc6cc65 100644
--- a/rezag/handlers.py
+++ b/rezag/handlers.py
@@ -39,12 +39,13 @@ class IndexHandler(object):
         self.opts = opts or {}
 
     def get_supported_modes(self):
-        return dict(modes=['list_modes', 'list_sources', 'index'])
+        return dict(modes=['list_sources', 'index'])
 
     def _load_index_source(self, params):
         url = params.get('url')
         if not url:
-            raise BadRequestException('The "url" param is required')
+            errs = dict(last_exc=BadRequestException('The "url" param is required'))
+            return None, errs
 
         input_req = params.get('_input_req')
         if input_req:
@@ -55,21 +56,25 @@ class IndexHandler(object):
     def __call__(self, params):
         mode = params.get('mode', 'index')
         if mode == 'list_sources':
-            return self.index_source.get_source_list(params)
+            return self.index_source.get_source_list(params), {}
 
-        if mode == 'list_modes' or mode != 'index':
-            return self.get_supported_modes()
+        if mode != 'index':
+            return self.get_supported_modes(), {}
 
         output = params.get('output', self.DEF_OUTPUT)
         fields = params.get('fields')
 
         handler = self.OUTPUTS.get(output)
         if not handler:
-            raise BadRequestException('output={0} not supported'.format(output))
+            errs = dict(last_exc=BadRequestException('output={0} not supported'.format(output)))
+            return None, errs
+
+        cdx_iter, errs = self._load_index_source(params)
+        if not cdx_iter:
+            return None, errs
 
-        cdx_iter = self._load_index_source(params)
         res = handler(cdx_iter, fields)
-        return res
+        return res, errs
 
 
 #=============================================================================
@@ -87,7 +92,10 @@ class ResourceHandler(IndexHandler):
         if params.get('mode', 'resource') != 'resource':
             return super(ResourceHandler, self).__call__(params)
 
-        cdx_iter = self._load_index_source(params)
+        cdx_iter, errs = self._load_index_source(params)
+        if not cdx_iter:
+            return None, errs
+
         last_exc = None
 
         for cdx in cdx_iter:
@@ -95,15 +103,15 @@ class ResourceHandler(IndexHandler):
                 try:
                     resp = loader(cdx, params)
                     if resp is not None:
-                        return resp
+                        return resp, errs
                 except WbException as e:
                     last_exc = e
+                    errs[str(loader)] = repr(e)
 
         if last_exc:
-            raise last_exc
-            #raise ArchiveLoadFailed('Resource Found, could not be Loaded')
-        else:
-            raise NotFoundException('No Resource Found')
+            errs['last_exc'] = last_exc
+
+        return None, errs
 
 
 #=============================================================================
@@ -121,20 +129,19 @@ class HandlerSeq(object):
         self.handlers = handlers
 
     def get_supported_modes(self):
-        return []
-    #    return zip([self.handlers.get_supported_modes()]
+        if self.handlers:
+            return self.handlers[0].get_supported_modes()
+        else:
+            return {}
 
     def __call__(self, params):
-        last_exc = None
+        all_errs = {}
         for handler in self.handlers:
-            try:
-                res = handler(params)
-                if res is not None:
-                    return res
-            except WbException as e:
-                last_exc = e
+            res, errs = handler(params)
+            all_errs.update(errs)
+            if res is not None:
+                return res, all_errs
+
+        return None, all_errs
+
 
-        if last_exc:
-            raise last_exc
-        else:
-            raise NotFoundException('No Resource Found')
diff --git a/rezag/responseloader.py b/rezag/responseloader.py
index ed4cc6aa..c3c6dd5c 100644
--- a/rezag/responseloader.py
+++ b/rezag/responseloader.py
@@ -58,6 +58,10 @@ class WARCPathLoader(object):
                                               no_record_parse=True)
         self.cdx_source = cdx_source
 
+    def cdx_index_source(self, *args, **kwargs):
+        cdx_iter, errs = self.cdx_source(*args, **kwargs)
+        return cdx_iter
+
     def warc_paths(self):
         for path in self.paths:
             def check(filename, cdx):
@@ -83,7 +87,7 @@ class WARCPathLoader(object):
         headers, payload = (self.resolve_loader.
                              load_headers_and_payload(cdx,
                                                       failed_files,
-                                                      self.cdx_source))
+                                                      self.cdx_index_source))
 
         record = payload
 
@@ -102,6 +106,9 @@ class WARCPathLoader(object):
         res = StreamIter(record.stream)
         return res
 
+    def __str__(self):
+        return  'WARCPathLoader'
+
 
 #=============================================================================
 class HeaderRecorder(BaseRecorder):
@@ -200,3 +207,7 @@ class LiveWebLoader(object):
         if not id_:
             id_ = uuid.uuid1()
         return '<urn:uuid:{0}>'.format(id_)
+
+    def __str__(self):
+        return  'LiveWebLoader'
+
diff --git a/rezag/utils.py b/rezag/utils.py
index ab44aa4e..94c67975 100644
--- a/rezag/utils.py
+++ b/rezag/utils.py
@@ -2,7 +2,7 @@ import re
 import six
 
 from pywb.utils.timeutils import timestamp_to_http_date
-
+from pywb.utils.wbexception import BadRequestException
 
 LINK_SPLIT = re.compile(',\s*(?=[<])')
 LINK_SEG_SPLIT = re.compile(';\s*')
@@ -10,6 +10,11 @@ LINK_URL = re.compile('<(.*)>')
 LINK_PROP = re.compile('([\w]+)="([^"]+)')
 
 
+#=================================================================
+class MementoException(BadRequestException):
+    pass
+
+
 #=================================================================
 class MementoUtils(object):
     @staticmethod
@@ -22,7 +27,7 @@ class MementoUtils(object):
             props = LINK_SEG_SPLIT.split(link)
             m = LINK_URL.match(props[0])
             if not m:
-                raise Exception('Invalid Link Url: ' + props[0])
+                raise MementoException('Invalid Link Url: ' + props[0])
 
             result = dict(url=m.group(1))
             key = ''
@@ -31,7 +36,7 @@ class MementoUtils(object):
             for prop in props[1:]:
                 m = LINK_PROP.match(prop)
                 if not m:
-                    raise Exception('Invalid prop ' + prop)
+                    raise MementoException('Invalid prop ' + prop)
 
                 name = m.group(1)
                 value = m.group(2)
diff --git a/test/test_dir_agg.py b/test/test_dir_agg.py
index 6ec1c6a4..7fe75920 100644
--- a/test/test_dir_agg.py
+++ b/test/test_dir_agg.py
@@ -59,43 +59,47 @@ def to_json_list(cdxlist, fields=['timestamp', 'load_url', 'filename', 'source']
 
 
 def test_agg_no_coll_set():
-    res = dir_loader(dict(url='example.com/'))
+    res, errs = dir_loader(dict(url='example.com/'))
     assert(to_json_list(res) == [])
-
+    assert(errs == {})
 
 def test_agg_collA_found():
-    res = dir_loader({'url': 'example.com/', 'param.coll': 'A'})
+    res, errs = dir_loader({'url': 'example.com/', 'param.coll': 'A'})
 
     exp = [{'source': 'colls/A/indexes', 'timestamp': '20160225042329', 'filename': 'example.warc.gz'}]
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 def test_agg_collB():
-    res = dir_loader({'url': 'example.com/', 'param.coll': 'B'})
+    res, errs = dir_loader({'url': 'example.com/', 'param.coll': 'B'})
 
     exp = []
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 def test_agg_collB_found():
-    res = dir_loader({'url': 'iana.org/', 'param.coll': 'B'})
+    res, errs = dir_loader({'url': 'iana.org/', 'param.coll': 'B'})
 
     exp = [{'source': 'colls/B/indexes', 'timestamp': '20140126200624', 'filename': 'iana.warc.gz'}]
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 def test_extra_agg_collB():
     agg_source = SimpleAggregator({'dir': dir_loader})
-    res = agg_source({'url': 'iana.org/', 'param.coll': 'B'})
+    res, errs = agg_source({'url': 'iana.org/', 'param.coll': 'B'})
 
     exp = [{'source': 'dir:colls/B/indexes', 'timestamp': '20140126200624', 'filename': 'iana.warc.gz'}]
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 def test_agg_all_found_1():
-    res = dir_loader({'url': 'iana.org/', 'param.coll': '*'})
+    res, errs = dir_loader({'url': 'iana.org/', 'param.coll': '*'})
 
     exp = [
         {'source': 'colls/B/indexes', 'timestamp': '20140126200624', 'filename': 'iana.warc.gz'},
@@ -104,10 +108,11 @@ def test_agg_all_found_1():
     ]
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 def test_agg_all_found_2():
-    res = dir_loader({'url': 'example.com/', 'param.coll': '*'})
+    res, errs = dir_loader({'url': 'example.com/', 'param.coll': '*'})
 
     exp = [
         {'source': 'colls/C/indexes', 'timestamp': '20140127171200', 'filename': 'dupes.warc.gz'},
@@ -116,6 +121,7 @@ def test_agg_all_found_2():
     ]
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 
@@ -124,7 +130,7 @@ def test_agg_dir_and_memento():
                'local': dir_loader}
     agg_source = SimpleAggregator(sources)
 
-    res = agg_source({'url': 'example.com/', 'param.local.coll': '*', 'closest': '20100512', 'limit': 6})
+    res, errs = agg_source({'url': 'example.com/', 'param.local.coll': '*', 'closest': '20100512', 'limit': 6})
 
     exp = [
         {'source': 'ia', 'timestamp': '20100513052358', 'load_url': 'http://web.archive.org/web/20100513052358id_/http://example.com/'},
@@ -136,23 +142,26 @@ def test_agg_dir_and_memento():
     ]
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 def test_agg_no_dir_1():
-    res = dir_loader({'url': 'example.com/', 'param.coll': 'X'})
+    res, errs = dir_loader({'url': 'example.com/', 'param.coll': 'X'})
 
     exp = []
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 def test_agg_no_dir_2():
     loader = DirectoryIndexSource(root_dir, '')
-    res = loader({'url': 'example.com/', 'param.coll': 'X'})
+    res, errs = loader({'url': 'example.com/', 'param.coll': 'X'})
 
     exp = []
 
     assert(to_json_list(res) == exp)
+    assert(errs == {})
 
 
 def test_agg_dir_sources_1():
diff --git a/test/test_handlers.py b/test/test_handlers.py
index 55d63d62..3e911224 100644
--- a/test/test_handlers.py
+++ b/test/test_handlers.py
@@ -50,7 +50,7 @@ def setup_module(self):
                                   handler2]))
 
     add_route('/empty', HandlerSeq([]))
-    add_route('/invalid', HandlerSeq(['foo']))
+    add_route('/invalid', DefaultResourceHandler([SimpleAggregator({'invalid': 'should not be a callable'})]))
 
     application.debug = True
     global testapp
@@ -65,23 +65,49 @@ class TestResAgg(object):
     def setup(self):
         self.testapp = testapp
 
+    def test_list_routes(self):
+        resp = self.testapp.get('/')
+        res = resp.json
+        assert set(res.keys()) == set(['/empty', '/empty/postreq',
+                                       '/fallback', '/fallback/postreq',
+                                       '/live', '/live/postreq',
+                                       '/many', '/many/postreq',
+                                       '/posttest', '/posttest/postreq',
+                                       '/seq', '/seq/postreq',
+                                       '/invalid', '/invalid/postreq'])
+
+        assert res['/fallback'] == {'modes': ['list_sources', 'index', 'resource']}
+
     def test_list_handlers(self):
-        resp = self.testapp.get('/many?mode=list_modes')
-        assert resp.json == {'modes': ['list_modes', 'list_sources', 'index', 'resource']}
+        resp = self.testapp.get('/many')
+        assert resp.json == {'modes': ['list_sources', 'index', 'resource']}
+        assert 'ResErrors' not in resp.headers
 
-        resp = self.testapp.get('/many?mode=other')
-        assert resp.json == {'modes': ['list_modes', 'list_sources', 'index', 'resource']}
+        resp = self.testapp.get('/many/other')
+        assert resp.json == {'modes': ['list_sources', 'index', 'resource']}
+        assert 'ResErrors' not in resp.headers
 
-        # defaults to resource, must specify url
-        resp = self.testapp.get('/many', status=400)
+    def test_list_errors(self):
+        # must specify url for index or resource
+        resp = self.testapp.get('/many/index', status=400)
         assert resp.json == {'message': 'The "url" param is required'}
+        assert resp.text == resp.headers['ResErrors']
+
+        resp = self.testapp.get('/many/index', status=400)
+        assert resp.json == {'message': 'The "url" param is required'}
+        assert resp.text == resp.headers['ResErrors']
+
+        resp = self.testapp.get('/many/resource', status=400)
+        assert resp.json == {'message': 'The "url" param is required'}
+        assert resp.text == resp.headers['ResErrors']
 
     def test_list_sources(self):
-        resp = self.testapp.get('/many?mode=list_sources')
+        resp = self.testapp.get('/many/list_sources')
         assert resp.json == {'sources': {'local': 'file_dir', 'ia': 'memento', 'rhiz': 'memento', 'live': 'live'}}
+        assert 'ResErrors' not in resp.headers
 
     def test_live_index(self):
-        resp = self.testapp.get('/live?mode=index&url=http://httpbin.org/get&output=json')
+        resp = self.testapp.get('/live/index?url=http://httpbin.org/get&output=json')
         resp.charset = 'utf-8'
 
         res = to_json_list(resp.text)
@@ -91,7 +117,7 @@ class TestResAgg(object):
 
     def test_live_resource(self):
         headers = {'foo': 'bar'}
-        resp = self.testapp.get('/live?url=http://httpbin.org/get?foo=bar', headers=headers)
+        resp = self.testapp.get('/live/resource?url=http://httpbin.org/get?foo=bar', headers=headers)
 
         assert resp.headers['WARC-Coll'] == 'live'
         assert resp.headers['WARC-Target-URI'] == 'http://httpbin.org/get?foo=bar'
@@ -100,9 +126,10 @@ class TestResAgg(object):
         assert b'HTTP/1.1 200 OK' in resp.body
         assert b'"foo": "bar"' in resp.body
 
+        assert 'ResErrors' not in resp.headers
 
     def test_live_post_resource(self):
-        resp = self.testapp.post('/live?url=http://httpbin.org/post',
+        resp = self.testapp.post('/live/resource?url=http://httpbin.org/post',
                                  OrderedDict([('foo', 'bar')]))
 
         assert resp.headers['WARC-Coll'] == 'live'
@@ -112,38 +139,45 @@ class TestResAgg(object):
         assert b'HTTP/1.1 200 OK' in resp.body
         assert b'"foo": "bar"' in resp.body
 
+        assert 'ResErrors' not in resp.headers
+
     def test_agg_select_mem_1(self):
-        resp = self.testapp.get('/many?url=http://vvork.com/&closest=20141001')
+        resp = self.testapp.get('/many/resource?url=http://vvork.com/&closest=20141001')
 
         assert resp.headers['WARC-Coll'] == 'rhiz'
         assert resp.headers['WARC-Target-URI'] == 'http://www.vvork.com/'
         assert resp.headers['WARC-Date'] == '2014-10-06T18:43:57Z'
         assert b'HTTP/1.1 200 OK' in resp.body
 
+        assert 'ResErrors' not in resp.headers
 
     def test_agg_select_mem_2(self):
-        resp = self.testapp.get('/many?url=http://vvork.com/&closest=20151231')
+        resp = self.testapp.get('/many/resource?url=http://vvork.com/&closest=20151231')
 
         assert resp.headers['WARC-Coll'] == 'ia'
         assert resp.headers['WARC-Target-URI'] == 'http://vvork.com/'
         assert resp.headers['WARC-Date'] == '2016-01-10T13:48:55Z'
         assert b'HTTP/1.1 200 OK' in resp.body
 
+        assert 'ResErrors' not in resp.headers
 
     def test_agg_select_live(self):
-        resp = self.testapp.get('/many?url=http://vvork.com/&closest=2016')
+        resp = self.testapp.get('/many/resource?url=http://vvork.com/&closest=2016')
 
         assert resp.headers['WARC-Coll'] == 'live'
         assert resp.headers['WARC-Target-URI'] == 'http://vvork.com/'
         assert resp.headers['WARC-Date'] != ''
 
+        assert 'ResErrors' not in resp.headers
+
     def test_agg_select_local(self):
-        resp = self.testapp.get('/many?url=http://iana.org/&closest=20140126200624')
+        resp = self.testapp.get('/many/resource?url=http://iana.org/&closest=20140126200624')
 
         assert resp.headers['WARC-Coll'] == 'local'
         assert resp.headers['WARC-Target-URI'] == 'http://www.iana.org/'
         assert resp.headers['WARC-Date'] == '2014-01-26T20:06:24Z'
 
+        assert json.loads(resp.headers['ResErrors']) == {"rhiz": "NotFoundException('http://webenact.rhizome.org/vvork/http://iana.org/',)"}
 
     def test_agg_select_local_postreq(self):
         req_data = """\
@@ -153,12 +187,13 @@ User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/537.36 (
 Host: iana.org
 """
 
-        resp = self.testapp.post('/many/postreq?url=http://iana.org/&closest=20140126200624', req_data)
+        resp = self.testapp.post('/many/resource/postreq?url=http://iana.org/&closest=20140126200624', req_data)
 
         assert resp.headers['WARC-Coll'] == 'local'
         assert resp.headers['WARC-Target-URI'] == 'http://www.iana.org/'
         assert resp.headers['WARC-Date'] == '2014-01-26T20:06:24Z'
 
+        assert json.loads(resp.headers['ResErrors']) == {"rhiz": "NotFoundException('http://webenact.rhizome.org/vvork/http://iana.org/',)"}
 
     def test_agg_live_postreq(self):
         req_data = """\
@@ -168,7 +203,7 @@ User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/537.36 (
 Host: httpbin.org
 """
 
-        resp = self.testapp.post('/many/postreq?url=http://httpbin.org/get?foo=bar&closest=now', req_data)
+        resp = self.testapp.post('/many/resource/postreq?url=http://httpbin.org/get?foo=bar&closest=now', req_data)
 
         assert resp.headers['WARC-Coll'] == 'live'
         assert resp.headers['WARC-Target-URI'] == 'http://httpbin.org/get?foo=bar'
@@ -177,6 +212,8 @@ Host: httpbin.org
         assert b'HTTP/1.1 200 OK' in resp.body
         assert b'"foo": "bar"' in resp.body
 
+        assert json.loads(resp.headers['ResErrors']) == {"rhiz": "NotFoundException('http://webenact.rhizome.org/vvork/http://httpbin.org/get?foo=bar',)"}
+
     def test_agg_post_resolve_postreq(self):
         req_data = """\
 POST /post HTTP/1.1
@@ -188,7 +225,7 @@ content-type: application/x-www-form-urlencoded
 
 foo=bar&test=abc"""
 
-        resp = self.testapp.post('/posttest/postreq?url=http://httpbin.org/post', req_data)
+        resp = self.testapp.post('/posttest/resource/postreq?url=http://httpbin.org/post', req_data)
 
         assert resp.headers['WARC-Coll'] == 'post'
         assert resp.headers['WARC-Target-URI'] == 'http://httpbin.org/post'
@@ -197,10 +234,12 @@ foo=bar&test=abc"""
         assert b'"test": "abc"' in resp.body
         assert b'"url": "http://httpbin.org/post"' in resp.body
 
+        assert 'ResErrors' not in resp.headers
+
     def test_agg_post_resolve_fallback(self):
         req_data = OrderedDict([('foo', 'bar'), ('test', 'abc')])
 
-        resp = self.testapp.post('/fallback?url=http://httpbin.org/post', req_data)
+        resp = self.testapp.post('/fallback/resource?url=http://httpbin.org/post', req_data)
 
         assert resp.headers['WARC-Coll'] == 'post'
         assert resp.headers['WARC-Target-URI'] == 'http://httpbin.org/post'
@@ -209,28 +248,37 @@ foo=bar&test=abc"""
         assert b'"test": "abc"' in resp.body
         assert b'"url": "http://httpbin.org/post"' in resp.body
 
+        assert 'ResErrors' not in resp.headers
+
     def test_agg_seq_fallback_1(self):
-        resp = self.testapp.get('/fallback?url=http://www.iana.org/')
+        resp = self.testapp.get('/fallback/resource?url=http://www.iana.org/')
 
         assert resp.headers['WARC-Coll'] == 'live'
         assert resp.headers['WARC-Target-URI'] == 'http://www.iana.org/'
         assert b'HTTP/1.1 200 OK' in resp.body
 
+        assert 'ResErrors' not in resp.headers
+
     def test_agg_seq_fallback_2(self):
-        resp = self.testapp.get('/fallback?url=http://www.example.com/')
+        resp = self.testapp.get('/fallback/resource?url=http://www.example.com/')
 
         assert resp.headers['WARC-Coll'] == 'example'
         assert resp.headers['WARC-Date'] == '2016-02-25T04:23:29Z'
         assert resp.headers['WARC-Target-URI'] == 'http://example.com/'
         assert b'HTTP/1.1 200 OK' in resp.body
 
-    def test_error_fallback_live_not_found(self):
-        resp = self.testapp.get('/fallback?url=http://invalid.url-not-found', status=400)
+        assert 'ResErrors' not in resp.headers
 
-        assert resp.json == {'message': 'http://invalid.url-not-found'}
+    def test_error_fallback_live_not_found(self):
+        resp = self.testapp.get('/fallback/resource?url=http://invalid.url-not-found', status=400)
+
+        assert resp.json == {'message': 'http://invalid.url-not-found',
+                             'errors': {'LiveWebLoader': "LiveResourceException('http://invalid.url-not-found',)"}}
+
+        assert resp.text == resp.headers['ResErrors']
 
     def test_agg_local_revisit(self):
-        resp = self.testapp.get('/many?url=http://www.example.com/&closest=20140127171251&sources=local')
+        resp = self.testapp.get('/many/resource?url=http://www.example.com/&closest=20140127171251&sources=local')
 
         assert resp.headers['WARC-Coll'] == 'local'
         assert resp.headers['WARC-Target-URI'] == 'http://example.com'
@@ -240,23 +288,30 @@ foo=bar&test=abc"""
         assert b'HTTP/1.1 200 OK' in resp.body
         assert b'<!doctype html>' in resp.body
 
+        assert 'ResErrors' not in resp.headers
+
     def test_error_invalid_index_output(self):
-        resp = self.testapp.get('/live?mode=index&url=http://httpbin.org/get&output=foobar', status=400)
+        resp = self.testapp.get('/live/index?url=http://httpbin.org/get&output=foobar', status=400)
 
         assert resp.json == {'message': 'output=foobar not supported'}
+        assert resp.text == resp.headers['ResErrors']
 
     def test_error_local_not_found(self):
-        resp = self.testapp.get('/many?url=http://not-found.error/&sources=local', status=404)
+        resp = self.testapp.get('/many/resource?url=http://not-found.error/&sources=local', status=404)
 
         assert resp.json == {'message': 'No Resource Found'}
+        assert resp.text == resp.headers['ResErrors']
 
     def test_error_empty(self):
-        resp = self.testapp.get('/empty?url=http://example.com/', status=404)
+        resp = self.testapp.get('/empty/resource?url=http://example.com/', status=404)
 
         assert resp.json == {'message': 'No Resource Found'}
+        assert resp.text == resp.headers['ResErrors']
 
     def test_error_invalid(self):
-        resp = self.testapp.get('/invalid?url=http://example.com/', status=500)
+        resp = self.testapp.get('/invalid/resource?url=http://example.com/', status=500)
+
+        assert resp.json == {'message': "Internal Error: 'list' object is not callable"}
+        assert resp.text == resp.headers['ResErrors']
 
-        assert resp.json['message'].startswith('Internal Error')
 
diff --git a/test/test_indexsource.py b/test/test_indexsource.py
index 5853f02c..b69206cd 100644
--- a/test/test_indexsource.py
+++ b/test/test_indexsource.py
@@ -55,7 +55,7 @@ def query_single_source(source, params):
 @pytest.mark.parametrize("source", local_sources, ids=["file", "redis"])
 def test_local_cdxj_loader(source):
     url = 'http://www.iana.org/_css/2013.1/fonts/Inconsolata.otf'
-    res = query_single_source(source, dict(url=url, limit=3))
+    res, errs = query_single_source(source, dict(url=url, limit=3))
 
     expected = """\
 org,iana)/_css/2013.1/fonts/inconsolata.otf 20140126200826 iana.warc.gz
@@ -63,6 +63,7 @@ org,iana)/_css/2013.1/fonts/inconsolata.otf 20140126200912 iana.warc.gz
 org,iana)/_css/2013.1/fonts/inconsolata.otf 20140126200930 iana.warc.gz"""
 
     assert(key_ts_res(res) == expected)
+    assert(errs == {})
 
 
 # Closest -- Local Loaders
@@ -70,7 +71,7 @@ org,iana)/_css/2013.1/fonts/inconsolata.otf 20140126200930 iana.warc.gz"""
 @pytest.mark.parametrize("source", local_sources, ids=["file", "redis"])
 def test_local_closest_loader(source):
     url = 'http://www.iana.org/_css/2013.1/fonts/Inconsolata.otf'
-    res = query_single_source(source, dict(url=url,
+    res, errs = query_single_source(source, dict(url=url,
                   closest='20140126200930',
                   limit=3))
 
@@ -80,13 +81,14 @@ org,iana)/_css/2013.1/fonts/inconsolata.otf 20140126200912 iana.warc.gz
 org,iana)/_css/2013.1/fonts/inconsolata.otf 20140126200826 iana.warc.gz"""
 
     assert(key_ts_res(res) == expected)
+    assert(errs == {})
 
 
 # Prefix -- Local Loaders
 # ============================================================================
 @pytest.mark.parametrize("source", local_sources, ids=["file", "redis"])
 def test_file_prefix_loader(source):
-    res = query_single_source(source, dict(url='http://iana.org/domains/root/*'))
+    res, errs = query_single_source(source, dict(url='http://iana.org/domains/root/*'))
 
     expected = """\
 org,iana)/domains/root/db 20140126200927 iana.warc.gz
@@ -94,6 +96,7 @@ org,iana)/domains/root/db 20140126200928 iana.warc.gz
 org,iana)/domains/root/servers 20140126201227 iana.warc.gz"""
 
     assert(key_ts_res(res) == expected)
+    assert(errs == {})
 
 
 # Url Match -- Remote Loaders
@@ -101,7 +104,7 @@ org,iana)/domains/root/servers 20140126201227 iana.warc.gz"""
 @pytest.mark.parametrize("source", remote_sources, ids=["remote_cdx", "memento"])
 def test_remote_loader(source):
     url = 'http://instagram.com/amaliaulman'
-    res = query_single_source(source, dict(url=url))
+    res, errs = query_single_source(source, dict(url=url))
 
     expected = """\
 com,instagram)/amaliaulman 20141014150552 http://webenact.rhizome.org/all/20141014150552id_/http://instagram.com/amaliaulman
@@ -110,6 +113,7 @@ com,instagram)/amaliaulman 20141014162333 http://webenact.rhizome.org/all/201410
 com,instagram)/amaliaulman 20141014171636 http://webenact.rhizome.org/all/20141014171636id_/http://instagram.com/amaliaulman"""
 
     assert(key_ts_res(res, 'load_url') == expected)
+    assert(errs == {})
 
 
 # Url Match -- Remote Loaders
@@ -117,12 +121,13 @@ com,instagram)/amaliaulman 20141014171636 http://webenact.rhizome.org/all/201410
 @pytest.mark.parametrize("source", remote_sources, ids=["remote_cdx", "memento"])
 def test_remote_closest_loader(source):
     url = 'http://instagram.com/amaliaulman'
-    res = query_single_source(source, dict(url=url, closest='20141014162332', limit=1))
+    res, errs = query_single_source(source, dict(url=url, closest='20141014162332', limit=1))
 
     expected = """\
 com,instagram)/amaliaulman 20141014162333 http://webenact.rhizome.org/all/20141014162333id_/http://instagram.com/amaliaulman"""
 
     assert(key_ts_res(res, 'load_url') == expected)
+    assert(errs == {})
 
 
 # Url Match -- Memento
@@ -130,25 +135,26 @@ com,instagram)/amaliaulman 20141014162333 http://webenact.rhizome.org/all/201410
 @pytest.mark.parametrize("source", remote_sources, ids=["remote_cdx", "memento"])
 def test_remote_closest_loader(source):
     url = 'http://instagram.com/amaliaulman'
-    res = query_single_source(source, dict(url=url, closest='20141014162332', limit=1))
+    res, errs = query_single_source(source, dict(url=url, closest='20141014162332', limit=1))
 
     expected = """\
 com,instagram)/amaliaulman 20141014162333 http://webenact.rhizome.org/all/20141014162333id_/http://instagram.com/amaliaulman"""
 
     assert(key_ts_res(res, 'load_url') == expected)
+    assert(errs == {})
+
 
 # Live Index -- No Load!
 # ============================================================================
 def test_live():
     url = 'http://example.com/'
     source = LiveIndexSource()
-    res = query_single_source(source, dict(url=url))
+    res, errs = query_single_source(source, dict(url=url))
 
     expected = 'com,example)/ {0} http://example.com/'.format(timestamp_now())
 
     assert(key_ts_res(res, 'load_url') == expected)
-
-
+    assert(errs == {})
 
 
 # Errors -- Not Found All
@@ -156,31 +162,36 @@ def test_live():
 @pytest.mark.parametrize("source", local_sources + remote_sources, ids=["file", "redis", "remote_cdx", "memento"])
 def test_all_not_found(source):
     url = 'http://x-not-found-x.notfound/'
-    res = query_single_source(source, dict(url=url, limit=3))
+    res, errs = query_single_source(source, dict(url=url, limit=3))
 
     expected = ''
     assert(key_ts_res(res) == expected)
+    if source == remote_sources[0]:
+        assert('http://x-not-found-x.notfound/' in errs['source'])
+    else:
+        assert(errs == {})
 
 
 # ============================================================================
 def test_another_remote_not_found():
     source = MementoIndexSource.from_timegate_url('http://www.webarchive.org.uk/wayback/archive/')
     url = 'http://x-not-found-x.notfound/'
-    res = query_single_source(source, dict(url=url, limit=3))
+    res, errs = query_single_source(source, dict(url=url, limit=3))
 
 
     expected = ''
     assert(key_ts_res(res) == expected)
-
+    assert(errs['source'] == "NotFoundException('http://www.webarchive.org.uk/wayback/archive/timemap/link/http://x-not-found-x.notfound/',)")
 
 # ============================================================================
 def test_file_not_found():
     source = FileIndexSource('testdata/not-found-x')
     url = 'http://x-not-found-x.notfound/'
-    res = query_single_source(source, dict(url=url, limit=3))
+    res, errs = query_single_source(source, dict(url=url, limit=3))
 
     expected = ''
     assert(key_ts_res(res) == expected)
+    assert(errs['source'] == "NotFoundException('testdata/not-found-x',)"), errs
 
 
 # ============================================================================
@@ -188,7 +199,7 @@ def test_ait_filters():
     ait_source = RemoteIndexSource('http://wayback.archive-it.org/cdx/search/cdx?url={url}&filter=filename:ARCHIVEIT-({colls})-.*',
                                    'http://wayback.archive-it.org/all/{timestamp}id_/{url}')
 
-    cdxlist = query_single_source(ait_source, {'url': 'http://iana.org/', 'param.source.colls': '5610|933'})
+    cdxlist, errs = query_single_source(ait_source, {'url': 'http://iana.org/', 'param.source.colls': '5610|933'})
     filenames = [cdx['filename'] for cdx in cdxlist]
 
     prefix = ('ARCHIVEIT-5610-', 'ARCHIVEIT-933-')
@@ -196,7 +207,7 @@ def test_ait_filters():
     assert(all([x.startswith(prefix) for x in filenames]))
 
 
-    cdxlist = query_single_source(ait_source, {'url': 'http://iana.org/', 'param.source.colls': '1883|366|905'})
+    cdxlist, errs = query_single_source(ait_source, {'url': 'http://iana.org/', 'param.source.colls': '1883|366|905'})
     filenames = [cdx['filename'] for cdx in cdxlist]
 
     prefix = ('ARCHIVEIT-1883-', 'ARCHIVEIT-366-', 'ARCHIVEIT-905-')
diff --git a/test/test_memento_agg.py b/test/test_memento_agg.py
index 9a1b9209..0e5ded7c 100644
--- a/test/test_memento_agg.py
+++ b/test/test_memento_agg.py
@@ -1,13 +1,14 @@
 from gevent import monkey; monkey.patch_all(thread=False)
 
 from rezag.aggindexsource import SimpleAggregator, GeventTimeoutAggregator
-from rezag.aggindexsource import ThreadedTimeoutAggregator
+from rezag.aggindexsource import ThreadedTimeoutAggregator, BaseAggregator
 
 from rezag.indexsource import FileIndexSource, RemoteIndexSource, MementoIndexSource
 from .testutils import json_list, to_path
 
 import json
 import pytest
+import time
 
 from rezag.handlers import IndexHandler
 
@@ -27,6 +28,10 @@ aggs = {'simple': SimpleAggregator(sources),
         'processes': ThreadedTimeoutAggregator(sources, timeout=5.0, use_processes=True),
        }
 
+agg_tm = {'gevent': GeventTimeoutAggregator(sources, timeout=0.0),
+          'threaded': ThreadedTimeoutAggregator(sources, timeout=0.0),
+          'processes': ThreadedTimeoutAggregator(sources, timeout=0.0, use_processes=True)}
+
 nf = {'notfound': FileIndexSource(to_path('testdata/not-found-x'))}
 agg_nf = {'simple': SimpleAggregator(nf),
           'gevent': GeventTimeoutAggregator(nf, timeout=5.0),
@@ -41,7 +46,7 @@ agg_nf = {'simple': SimpleAggregator(nf),
 @pytest.mark.parametrize("agg", list(aggs.values()), ids=list(aggs.keys()))
 def test_mem_agg_index_1(agg):
     url = 'http://iana.org/'
-    res = agg(dict(url=url, closest='20140126000000', limit=5))
+    res, errs = agg(dict(url=url, closest='20140126000000', limit=5))
 
 
     exp = [{"timestamp": "20140126093743", "load_url": "http://web.archive.org/web/20140126093743id_/http://iana.org/", "source": "ia"},
@@ -52,12 +57,13 @@ def test_mem_agg_index_1(agg):
           ]
 
     assert(json_list(res) == exp)
-
+    assert(errs == {'bl': "NotFoundException('http://www.webarchive.org.uk/wayback/archive/http://iana.org/',)",
+                    'rhiz': "NotFoundException('http://webenact.rhizome.org/vvork/http://iana.org/',)"})
 
 @pytest.mark.parametrize("agg", list(aggs.values()), ids=list(aggs.keys()))
 def test_mem_agg_index_2(agg):
     url = 'http://example.com/'
-    res = agg(dict(url=url, closest='20100512', limit=6))
+    res, errs = agg(dict(url=url, closest='20100512', limit=6))
 
     exp = [{"timestamp": "20100513010014", "load_url": "http://www.webarchive.org.uk/wayback/archive/20100513010014id_/http://example.com/", "source": "bl"},
             {"timestamp": "20100512204410", "load_url": "http://www.webarchive.org.uk/wayback/archive/20100512204410id_/http://example.com/", "source": "bl"},
@@ -67,12 +73,13 @@ def test_mem_agg_index_2(agg):
             {"timestamp": "20100514231857", "load_url": "http://web.archive.org/web/20100514231857id_/http://example.com/", "source": "ia"}]
 
     assert(json_list(res) == exp)
+    assert(errs == {'rhiz': "NotFoundException('http://webenact.rhizome.org/vvork/http://example.com/',)"})
 
 
 @pytest.mark.parametrize("agg", list(aggs.values()), ids=list(aggs.keys()))
 def test_mem_agg_index_3(agg):
     url = 'http://vvork.com/'
-    res = agg(dict(url=url, closest='20141001', limit=5))
+    res, errs = agg(dict(url=url, closest='20141001', limit=5))
 
     exp = [{"timestamp": "20141006184357", "load_url": "http://webenact.rhizome.org/vvork/20141006184357id_/http://www.vvork.com/", "source": "rhiz"},
            {"timestamp": "20141018133107", "load_url": "http://web.archive.org/web/20141018133107id_/http://vvork.com/", "source": "ia"},
@@ -81,32 +88,53 @@ def test_mem_agg_index_3(agg):
            {"timestamp": "20131004231540", "load_url": "http://wayback.archive-it.org/all/20131004231540id_/http://vvork.com/", "source": "ait"}]
 
     assert(json_list(res) == exp)
+    assert(errs == {})
 
 
 @pytest.mark.parametrize("agg", list(aggs.values()), ids=list(aggs.keys()))
 def test_mem_agg_index_4(agg):
     url = 'http://vvork.com/'
-    res = agg(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait'))
+    res, errs = agg(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait'))
 
     exp = [{"timestamp": "20141006184357", "load_url": "http://webenact.rhizome.org/vvork/20141006184357id_/http://www.vvork.com/", "source": "rhiz"},
            {"timestamp": "20131004231540", "load_url": "http://wayback.archive-it.org/all/20131004231540id_/http://vvork.com/", "source": "ait"}]
 
     assert(json_list(res) == exp)
+    assert(errs == {})
 
 
 @pytest.mark.parametrize("agg", list(agg_nf.values()), ids=list(agg_nf.keys()))
 def test_mem_agg_not_found(agg):
     url = 'http://vvork.com/'
-    res = agg(dict(url=url, closest='20141001', limit=2))
+    res, errs = agg(dict(url=url, closest='20141001', limit=2))
 
     assert(json_list(res) == [])
+    assert(errs == {'notfound': "NotFoundException('testdata/not-found-x',)"})
+
+
+@pytest.mark.parametrize("agg", list(agg_tm.values()), ids=list(agg_tm.keys()))
+def test_mem_agg_timeout(agg):
+    url = 'http://vvork.com/'
+
+    orig_source = BaseAggregator.load_child_source
+    def load_child_source(self, name, source, params):
+        time.sleep(0.1)
+        return orig_source(name, source, params)
+
+    BaseAggregator.load_child_source = load_child_source
+    res, errs = agg(dict(url=url, closest='20141001', limit=2))
+    BaseAggregator.load_child_source = orig_source
+
+    assert(json_list(res) == [])
+    assert(errs == {'local': 'timeout',
+                    'ait': 'timeout', 'bl': 'timeout', 'ia': 'timeout', 'rhiz': 'timeout'})
 
 
 def test_handler_output_cdxj():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
     url = 'http://vvork.com/'
-    res = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait'))
+    res, errs = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait'))
 
     exp = """\
 com,vvork)/ 20141006184357 {"url": "http://www.vvork.com/", "mem_rel": "memento", "memento_url": "http://webenact.rhizome.org/vvork/20141006184357/http://www.vvork.com/", "load_url": "http://webenact.rhizome.org/vvork/20141006184357id_/http://www.vvork.com/", "source": "rhiz"}
@@ -114,13 +142,14 @@ com,vvork)/ 20131004231540 {"url": "http://vvork.com/", "mem_rel": "last memento
 """
 
     assert(''.join(res) == exp)
+    assert(errs == {})
 
 
 def test_handler_output_json():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
     url = 'http://vvork.com/'
-    res = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait', output='json'))
+    res, errs = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait', output='json'))
 
     exp = """\
 {"urlkey": "com,vvork)/", "timestamp": "20141006184357", "url": "http://www.vvork.com/", "mem_rel": "memento", "memento_url": "http://webenact.rhizome.org/vvork/20141006184357/http://www.vvork.com/", "load_url": "http://webenact.rhizome.org/vvork/20141006184357id_/http://www.vvork.com/", "source": "rhiz"}
@@ -128,26 +157,27 @@ def test_handler_output_json():
 """
 
     assert(''.join(res) == exp)
-
+    assert(errs == {})
 
 def test_handler_output_link():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
     url = 'http://vvork.com/'
-    res = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait', output='link'))
+    res, errs = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait', output='link'))
 
     exp = """\
 <http://webenact.rhizome.org/vvork/20141006184357id_/http://www.vvork.com/>; rel="memento"; datetime="Mon, 06 Oct 2014 18:43:57 GMT"; src="rhiz",
 <http://wayback.archive-it.org/all/20131004231540id_/http://vvork.com/>; rel="memento"; datetime="Fri, 04 Oct 2013 23:15:40 GMT"; src="ait"
 """
     assert(''.join(res) == exp)
+    assert(errs == {})
 
 
 def test_handler_output_link_2():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
     url = 'http://iana.org/'
-    res = handler(dict(url=url, closest='20140126000000', limit=5, output='link'))
+    res, errs = handler(dict(url=url, closest='20140126000000', limit=5, output='link'))
 
     exp = """\
 <http://web.archive.org/web/20140126093743id_/http://iana.org/>; rel="memento"; datetime="Sun, 26 Jan 2014 09:37:43 GMT"; src="ia",
@@ -158,38 +188,54 @@ def test_handler_output_link_2():
 """
     assert(''.join(res) == exp)
 
+    exp_errs = {'bl': "NotFoundException('http://www.webarchive.org.uk/wayback/archive/http://iana.org/',)",
+                'rhiz': "NotFoundException('http://webenact.rhizome.org/vvork/http://iana.org/',)"}
+
+    assert(errs == exp_errs)
+
+
 
 def test_handler_output_link_3():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
     url = 'http://foo.bar.non-existent'
-    res = handler(dict(url=url, closest='20140126000000', limit=5, output='link'))
+    res, errs = handler(dict(url=url, closest='20140126000000', limit=5, output='link'))
 
     exp = ''
 
     assert(''.join(res) == exp)
 
+    exp_errs = {'ait': "NotFoundException('http://wayback.archive-it.org/all/http://foo.bar.non-existent',)",
+                'bl': "NotFoundException('http://www.webarchive.org.uk/wayback/archive/http://foo.bar.non-existent',)",
+                'ia': "NotFoundException('http://web.archive.org/web/http://foo.bar.non-existent',)",
+                'rhiz': "NotFoundException('http://webenact.rhizome.org/vvork/http://foo.bar.non-existent',)"}
+
+    assert(errs == exp_errs)
+
 def test_handler_output_text():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
     url = 'http://vvork.com/'
-    res = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait', output='text'))
+    res, errs = handler(dict(url=url, closest='20141001', limit=2, sources='rhiz,ait', output='text'))
 
     exp = """\
 com,vvork)/ 20141006184357 http://www.vvork.com/ memento http://webenact.rhizome.org/vvork/20141006184357/http://www.vvork.com/ http://webenact.rhizome.org/vvork/20141006184357id_/http://www.vvork.com/ rhiz
 com,vvork)/ 20131004231540 http://vvork.com/ last memento http://wayback.archive-it.org/all/20131004231540/http://vvork.com/ http://wayback.archive-it.org/all/20131004231540id_/http://vvork.com/ ait
 """
     assert(''.join(res) == exp)
+    assert(errs == {})
 
 
 def test_handler_list_sources():
     agg = GeventTimeoutAggregator(sources, timeout=5.0)
     handler = IndexHandler(agg)
-    res = handler(dict(mode='list_sources'))
+    res, errs = handler(dict(mode='list_sources'))
 
     assert(res == {'sources': {'bl': 'memento',
                                'ait': 'memento',
                                'ia': 'memento',
                                'rhiz': 'memento',
                                'local': 'file'}})
+    assert(errs == {})
+
 
diff --git a/test/test_timeouts.py b/test/test_timeouts.py
index 6a96d464..263d21f3 100644
--- a/test/test_timeouts.py
+++ b/test/test_timeouts.py
@@ -35,7 +35,7 @@ def setup_module():
 def test_timeout_long_all_pass():
     agg = TimeoutAggregator(sources, timeout=1.0)
 
-    res = agg(dict(url='http://example.com/'))
+    res, errs = agg(dict(url='http://example.com/'))
 
     exp = [{'source': 'slower', 'timestamp': '20140127171200'},
            {'source': 'slower', 'timestamp': '20140127171251'},
@@ -43,27 +43,31 @@ def test_timeout_long_all_pass():
 
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
 
+    assert(errs == {})
+
 
 def test_timeout_slower_skipped_1():
     agg = GeventTimeoutAggregator(sources, timeout=0.49)
 
-    res = agg(dict(url='http://example.com/'))
+    res, errs = agg(dict(url='http://example.com/'))
 
     exp = [{'source': 'slow', 'timestamp': '20160225042329'}]
 
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
 
+    assert(errs == {'slower': 'timeout'})
 
 
 def test_timeout_slower_skipped_2():
     agg = GeventTimeoutAggregator(sources, timeout=0.19)
 
-    res = agg(dict(url='http://example.com/'))
+    res, errs = agg(dict(url='http://example.com/'))
 
     exp = []
 
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
 
+    assert(errs == {'slower': 'timeout', 'slow': 'timeout'})
 
 
 def test_timeout_skipping():
@@ -75,31 +79,40 @@ def test_timeout_skipping():
 
     exp = [{'source': 'slow', 'timestamp': '20160225042329'}]
 
-    res = agg(dict(url='http://example.com/'))
+    res, errs = agg(dict(url='http://example.com/'))
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
     assert(sources['slow'].calls == 4)
     assert(sources['slower'].calls == 4)
 
-    res = agg(dict(url='http://example.com/'))
+    assert(errs == {'slower': 'timeout'})
+
+    res, errs = agg(dict(url='http://example.com/'))
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
     assert(sources['slow'].calls == 5)
     assert(sources['slower'].calls == 5)
 
-    res = agg(dict(url='http://example.com/'))
+    assert(errs == {'slower': 'timeout'})
+
+    res, errs = agg(dict(url='http://example.com/'))
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
     assert(sources['slow'].calls == 6)
     assert(sources['slower'].calls == 5)
 
-    res = agg(dict(url='http://example.com/'))
+    assert(errs == {})
+
+    res, errs = agg(dict(url='http://example.com/'))
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
     assert(sources['slow'].calls == 7)
     assert(sources['slower'].calls == 5)
 
+    assert(errs == {})
+
     time.sleep(2.01)
 
-    res = agg(dict(url='http://example.com/'))
+    res, errs = agg(dict(url='http://example.com/'))
     assert(json_list(res, fields=['source', 'timestamp']) == exp)
     assert(sources['slow'].calls == 8)
     assert(sources['slower'].calls == 6)
 
+    assert(errs == {'slower': 'timeout'})