= Most Frequently Reported Bugs in Trac =

We have lots of tickets and lots of users, so it's not unlikely that sometimes a bug will be reported twice, or thrice, or ... dozens of times for some!

Here's a short list of the issues with a pathologically high duplicate rate:

 - #5028: '''!TracError: Unsupported version control system "svn"''' [[br]]
   search:'!TracError: Unsupported version control system "svn"' [[br]]
     ''This is not even a bug, rather an installation issue. The error means that for some reason, the Python bindings to the Subversion libraries couldn't be found or loaded. The TracSubversion page provides detailed [TracSubversion#Troubleshooting troubleshooting] information. In Trac [milestone:0.11], if this problem happens, it will only be reported as a warning for non-repository related pages. It's planned to improve the error message even further (#6796)''
 - #3839: '''Authentication information not available.''' [[br]]
   search:'Authentication information not available.' [[br]]
     ''Despite lots of information in the TracInstall and other places, there are still a lot of people being surprised by this message, which simply indicates that no authentication information has been setup for the server. How to actually set it depends on the actual form of the deployment, as mentioned in the [TracFaq#WhataboutthisAuthenticationinformationnotavailable.error FAQ].''
 - #3371: '''!RuntimeError: instance.!__dict!__ not accessible in restricted mode''' [[br]]
   search:"!RuntimeError: instance.__dict__ not accessible in restricted mode" [[br]]
     ''A problem inherent to the SWIG-based Subversion bindings when they are used from multiple Python interpreters in the same process. That situation can happen when the Trac server front-end is mod_python or mod_wsgi. See TracSubversion#instance-dict-restricted-mode for the mod_python instructions and mod_wsgi:IntegrationWithTrac for the mod_wsgi instructions.
 - #3446: '''Rate of `database is locked` errors is too high''' [[br]]
   search:"!OperationalError: database is locked" [[br]]
     ''This used to be a plague with the SQLite database backend, but it seems that things improved over time and this once !#1 duplicate bug is less frequent those days. A more scary variant of #3446 is #4929, where the lock situation seems to persist and needs a server restart (rare).''
 - #4311: '''Attaching files won't work with Trac < 0.10.4 and Python 2.5''' [[br]]
   search:"'cStringIO.StringO' object has no attribute 'len'" [[br]]
     ''This was a simple compatibility issue with Python 2.5, which was reported and fixed. It's surprising how people keep using old versions of the software and keep re-discovering the same bug over and over...''
 - #4365: '''SilverCity on t.e.o needs to be updated''' [[br]]
   search:'"HTMLParseError: bad end tag"' [[br]]
     ''Yes, we know, SilverCity has a bug which is apparently fixed in its version 0.9.7. See entry above ;-)''

 - #6976 '''!TypeError: cannot concatenate 'str' and '!NoneType' objects''' [[br]]
   search:"cannot concatenate 'str' and 'NoneType' objects" [[br]]
     ''This is a bug in the TH:GitPlugin for Trac on nonexistent paths, see TH:ticket:2671''