This affects a number of other OpenStack projects in a similar way, including:

- Neutron
- Cinder
- Glance

More projects may be affected that we are unaware of.

=====================================================
Example traceback from Neutron
=====================================================

2016-09-28 00:16:43.342 1218 DEBUG neutron.wsgi [-] (1218) accepted ('10.0.2.2', 50029) server /usr/local/lib/python2.7/dist-packages/eventlet/wsgi.py:868
Traceback (most recent call last):
  File "/usr/lib/python2.7/logging/__init__.py", line 851, in emit
    msg = self.format(record)
  File "/usr/local/lib/python2.7/dist-packages/oslo_log/handlers.py", line 76, in format
    return logging.StreamHandler.format(self, record)
  File "/usr/lib/python2.7/logging/__init__.py", line 724, in format
    return fmt.format(record)
  File "/usr/local/lib/python2.7/dist-packages/oslo_log/formatters.py", line 297, in format
    return logging.Formatter.format(self, record)
  File "/usr/lib/python2.7/logging/__init__.py", line 464, in format
    record.message = record.getMessage()
  File "/usr/lib/python2.7/logging/__init__.py", line 328, in getMessage
    msg = msg % self.args
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1164, in as_text
    bytes = self.as_bytes()
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1135, in as_bytes
    url = self.url
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 504, in url
    url = self.path_url
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 476, in path_url
    bpath_info = bytes_(self.path_info, self.url_encoding)
  File "/usr/local/lib/python2.7/dist-packages/webob/descriptors.py", line 68, in fget
    return req.encget(key, encattr=encattr)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 177, in encget
    return val.decode(encoding)
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xc0 in position 11: invalid start byte
Logged from file catch_errors.py, line 41
2016-09-28 00:16:43.489 1218 INFO neutron.wsgi [req-37cfe540-c134-4ec0-91d2-56687f38ffd5 admin -] 10.0.2.2 - - [28/Sep/2016 00:16:43] "PUT /v2.0/flavors/..%c0%af HTTP/1.1" 500 414 0.140984

=====================================================
Example traceback from Cinder
=====================================================

2016-09-27 23:50:00.142 5986 DEBUG eventlet.wsgi.server [-] (5986) accepted ('10.0.2.2', 49862) server /usr/local/lib/python2.7/dist-packages/eventlet/wsgi.py:868
2016-09-27 23:50:00.198 ERROR cinder.api.middleware.fault [req-7ec3610c-9cdc-4f7d-b69c-36c385d0fa10 admin] Caught error: <type 'exceptions.UnicodeDecodeError'> 'utf8' codec can't decode byte 0xc0 in position 3: invalid start byte
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault Traceback (most recent call last):
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/opt/stack/cinder/cinder/api/middleware/fault.py", line 79, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return req.get_response(self.application)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1299, in send
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     application, catch_exc_info=False)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1263, in call_application
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     app_iter = application(self.environ, start_response)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     resp = self.call_func(req, *args, **self.kwargs)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return self.func(req, *args, **kwargs)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/keystonemiddleware/auth_token/__init__.py", line 323, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     response = req.get_response(self._app)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1299, in send
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     application, catch_exc_info=False)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1263, in call_application
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     app_iter = application(self.environ, start_response)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 144, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return resp(environ, start_response)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 144, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return resp(environ, start_response)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/routes/middleware.py", line 141, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     response = self.app(environ, start_response)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 144, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return resp(environ, start_response)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     resp = self.call_func(req, *args, **self.kwargs)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return self.func(req, *args, **kwargs)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/opt/stack/cinder/cinder/api/openstack/wsgi.py", line 817, in __call__
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     "url": request.url})
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 504, in url
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     url = self.path_url
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 476, in path_url
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     bpath_info = bytes_(self.path_info, self.url_encoding)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/descriptors.py", line 68, in fget
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return req.encget(key, encattr=encattr)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 177, in encget
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return val.decode(encoding)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault   File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault     return codecs.utf_8_decode(input, errors, True)
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault UnicodeDecodeError: 'utf8' codec can't decode byte 0xc0 in position 3: invalid start byte
2016-09-27 23:50:00.198 5986 ERROR cinder.api.middleware.fault
2016-09-27 23:50:00.224 INFO eventlet.wsgi.server [req-7ec3610c-9cdc-4f7d-b69c-36c385d0fa10 admin] Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/eventlet/wsgi.py", line 481, in handle_one_response
    result = self.application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/paste/urlmap.py", line 216, in __call__
    return app(environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/oslo_middleware/base.py", line 126, in __call__
    response = req.get_response(self.application)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1299, in send
    application, catch_exc_info=False)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1263, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/oslo_middleware/base.py", line 126, in __call__
    response = req.get_response(self.application)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1299, in send
    application, catch_exc_info=False)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1263, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/oslo_middleware/request_id.py", line 37, in __call__
    response = req.get_response(self.application)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1299, in send
    application, catch_exc_info=False)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1263, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/opt/stack/cinder/cinder/api/middleware/fault.py", line 81, in __call__
    return self._error(ex, req)
  File "/opt/stack/cinder/cinder/api/middleware/fault.py", line 56, in _error
    msg_dict = dict(url=req.url, status=status)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 504, in url
    url = self.path_url
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 476, in path_url
    bpath_info = bytes_(self.path_info, self.url_encoding)
  File "/usr/local/lib/python2.7/dist-packages/webob/descriptors.py", line 68, in fget
    return req.encget(key, encattr=encattr)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 177, in encget
    return val.decode(encoding)
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xc0 in position 3: invalid start byte

2016-09-27 23:50:00.228 INFO eventlet.wsgi.server [req-7ec3610c-9cdc-4f7d-b69c-36c385d0fa10 admin] 10.0.2.2 "POST /v2/..%c0%af/backups HTTP/1.1" status: 500  len: 139 time: 0.0827849


=====================================================
Example traceback from Glance
=====================================================

2016-09-28 00:11:55.844 32495 INFO eventlet.wsgi.server [-] Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/eventlet/wsgi.py", line 481, in handle_one_response
    result = self.application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/oslo_middleware/base.py", line 126, in __call__
    response = req.get_response(self.application)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1299, in send
    application, catch_exc_info=False)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1263, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/oslo_middleware/base.py", line 123, in __call__
    response = self.process_request(req)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 148, in __call__
    return self.func(req, *args, **kw)
  File "/usr/local/lib/python2.7/dist-packages/oslo_middleware/healthcheck/__init__.py", line 361, in process_request
    if req.path != self._path:
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 485, in path
    bpath = bytes_(self.path_info, self.url_encoding)
  File "/usr/local/lib/python2.7/dist-packages/webob/descriptors.py", line 68, in fget
    return req.encget(key, encattr=encattr)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 177, in encget
    return val.decode(encoding)
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xc0 in position 13: invalid start byte

2016-09-28 00:11:55.854 32495 INFO eventlet.wsgi.server [-] 10.0.2.2 - - [28/Sep/2016 00:11:55] "GET /v2/images/..%c0%af/tags/..%c0%af HTTP/1.1" 500 139 0.043949


I'm not sure whether right approach here is to file a bug with webob (looks like there are several that haven't been resolved yet [1] [2]), or to fix this in each project's respective wsgi error-handling code.

[1] https://github.com/Pylons/webob/issues/115
[2] https://github.com/Pylons/webob/issues/161