Trac detected an internal error:

[jamsheer@…]

Trac detected an internal error:

​http://textbook.svnrepository.com/liftbridge_svn/trac.cgi/

Python Traceback

Traceback (most recent call last):
  File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 387, in dispatch_request
    dispatcher.dispatch(req)
  File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 191, in dispatch
    chosen_handler = self._pre_process_request(req, chosen_handler)
  File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 263, in _pre_process_request
    chosen_handler = f.pre_process_request(req, chosen_handler)
  File "/usr/lib/python2.3/site-packages/trac/versioncontrol/api.py", line 73, in pre_process_request
    self.get_repository(req.authname) # triggers a sync if applicable
  File "/usr/lib/python2.3/site-packages/trac/versioncontrol/api.py", line 101, in get_repository
    repos = self._connector.get_repository(rtype, rdir, authname)
  File "/usr/lib/python2.3/site-packages/trac/versioncontrol/svn_fs.py", line 260, in get_repository
    crepos = CachedRepository(self.env.get_db_cnx(), repos, None, self.log)
  File "/usr/lib/python2.3/site-packages/trac/versioncontrol/cache.py", line 34, in __init__
    self.sync()
  File "/usr/lib/python2.3/site-packages/trac/versioncontrol/cache.py", line 59, in sync
    raise TracError("The 'repository_dir' has changed, "
TracError: The 'repository_dir' has changed, a 'trac-admin resync' operation is needed.

[Emmanuel Blot]

As stated in the error message:
The 'repository_dir' has changed, a 'trac-admin resync' operation is needed.

This means that the Subversion repository has been changed, and the admin needs to run the specified command so that Trac is updated with this new repository.