Hello,

I've just upgraded from 1.9.5 to the latest 1.9.6 and I'm getting a 500 Internal Server error on every requests. In moin.log I can see these errors:

ERROR 2013-02-07 11:46:54,286 MoinMoin.wsgiapp:293 An exception has occurred [my_internal_link_omitted].
Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/MoinMoin/wsgiapp.py", line 282, in __call__
    response = run(context)
  File "/usr/lib/python2.6/site-packages/MoinMoin/wsgiapp.py", line 88, in run
    response = dispatch(request, context, action_name)
  File "/usr/lib/python2.6/site-packages/MoinMoin/wsgiapp.py", line 136, in dispatch
    response = handle_action(context, pagename, action_name)
  File "/usr/lib/python2.6/site-packages/MoinMoin/wsgiapp.py", line 195, in handle_action
    handler(context.page.page_name, context)
  File "/usr/lib/python2.6/site-packages/MoinMoin/action/__init__.py", line 258, in do_show
    if not request.user.may.read(pagename):
  File "/usr/lib/python2.6/site-packages/MoinMoin/security/__init__.py", line 150, in <lambda>
    return lambda pagename: _check(self.request, pagename, self.name, attr)
  File "/usr/lib/python2.6/site-packages/MoinMoin/security/__init__.py", line 85, in _check
    acl = p.getACL(request) # this will be fast in a reused page obj
  File "/usr/lib/python2.6/site-packages/MoinMoin/Page.py", line 1596, in getACL
    acl = self.parseACL()
  File "/usr/lib/python2.6/site-packages/MoinMoin/Page.py", line 1617, in parseACL
    return self.pi['acl']
  File "/usr/lib/python2.6/site-packages/MoinMoin/Page.py", line 252, in get_pi
    self.__pi = self.parse_processing_instructions()
  File "/usr/lib/python2.6/site-packages/MoinMoin/Page.py", line 917, in parse_processing_instructions
    if args in i18n.wikiLanguages():
TypeError: argument of type 'NoneType' is not iterable

Note that I'm using a wikifarm and I have this problem only on 3 of my instances - while 2 of them are working fine. They use the same underlay and static folders. Do you have any hints?

Thank you,
Nico