Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/trac/web/api.py", line 376, in send_error
    'text/html')
  File "/usr/lib/python2.6/dist-packages/trac/web/chrome.py", line 733, in render_template
    message = req.session.pop('chrome.%s.%d' % (type_, i))
  File "/usr/lib/python2.6/dist-packages/trac/web/api.py", line 195, in __getattr__
    value = self.callbacks[name](self)
  File "/usr/lib/python2.6/dist-packages/trac/web/main.py", line 265, in _get_session
    return Session(self.env, req)
  File "/usr/lib/python2.6/dist-packages/trac/web/session.py", line 157, in __init__
    self.get_session(sid)
  File "/usr/lib/python2.6/dist-packages/trac/web/session.py", line 178, in get_session
    super(Session, self).get_session(sid, authenticated)
  File "/usr/lib/python2.6/dist-packages/trac/web/session.py", line 51, in get_session
    db = self.env.get_db_cnx()
  File "/usr/lib/python2.6/dist-packages/trac/env.py", line 285, in get_db_cnx
    return DatabaseManager(self).get_connection()
  File "/usr/lib/python2.6/dist-packages/trac/db/api.py", line 92, in get_connection
    return self._cnx_pool.get_cnx(self.timeout or None)
  File "/usr/lib/python2.6/dist-packages/trac/db/pool.py", line 176, in get_cnx
    return _backend.get_cnx(self._connector, self._kwargs, timeout)
  File "/usr/lib/python2.6/dist-packages/trac/db/pool.py", line 109, in get_cnx
    cnx = connector.get_connection(**kwargs)
  File "/usr/lib/python2.6/dist-packages/trac/db/sqlite_backend.py", line 190, in get_connection
    return SQLiteConnection(path, log, params)
  File "/usr/lib/python2.6/dist-packages/trac/db/sqlite_backend.py", line 245, in __init__
    % (getuser(), path))
TracError: The user www-data requires read _and_ write permissions to the database file /opt/trac/project/db/trac.db and the directory it is located in.