AttributeError: 'NoneType' object has no attribute 'lower'

[ckujau]

How to Reproduce

While doing a GET operation on /, Trac issued an internal error.

(please provide additional details here)

User Agent was: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20100101 Firefox/13.0

System Information

Trac	0.11.7
Python	2.6.6 (r266:84292, Dec 26 2010, 22:31:48) [GCC 4.4.5]
setuptools	0.6
SQLite	3.7.3
pysqlite	2.4.1
Genshi	0.6
Pygments	1.3.1
Subversion	1.6.12 (r955767)
jQuery:	1.2.6

Python Traceback

Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/main.py", line 452, in _dispatch_request
    dispatcher.dispatch(req)
  File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/main.py", line 178, in dispatch
    chosen_handler)
  File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/main.py", line 298, in _pre_process_request
    chosen_handler = filter_.pre_process_request(req, chosen_handler)
  File "/usr/local/lib/python2.6/dist-packages/TracWikiNegotiator-1.6-py2.6.egg/wikinegotiator/negotiator.py", line 92, in pre_process_request
    page = self._decide_page(req)
  File "/usr/local/lib/python2.6/dist-packages/TracWikiNegotiator-1.6-py2.6.egg/wikinegotiator/negotiator.py", line 284, in _decide_page
    for lang in util.get_preferred_langs(req, self._default_lang):
  File "/usr/local/lib/python2.6/dist-packages/TracWikiNegotiator-1.6-py2.6.egg/wikinegotiator/util.py", line 112, in get_preferred_langs
    langs = _parse_langs(req.get_header('accept-language').lower()
AttributeError: 'NoneType' object has no attribute 'lower'

[ckujau]

This really about this Trac instance, _not_ about Xcache. I could not access " http://xcache.lighttpd.net" any more and the error message above is printed.

After digging around some more, I found the reason for this: I'm proxying through a Polipo Web-Proxy. When "censoredHeaders = accept-language" is set, the error message is printed and the frontpage of this Trac instance is not accessible any more. Disabling this option or accessing this page via https ( https://xcache.lighttpd.net/) helps.

So, again: not an Xcache issue, but enough to get annoyed. I wouldn't mind seeing this ticket closed, as it's now documented for anyone else having the same problem.

[moo]

thanks. this is fixed manually, will push to upstream later because upstream website is down for now. you may remind me when it's back:  http://trac-hacks.org/svn/tracwikinegotiatorplugin