Running Trac 0.12 on Ubuntu 10.04 - Error

I've installed trac 0.12 on my ubuntu 10.04, running the tracd internal webserver. When i access the page at http://127.0.0.1/myTracProject, I get the error message:

Traceback (most recent call last):   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/api.py", line 376, in send_error
    'text/html')   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/chrome.py", line 733, in render_template
    message = req.session.pop('chrome.%s.%d' % (type_, i))   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/api.py", line 195, in __getattr__
    value = self.callbacks[name](self)   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/main.py", line 265, in _get_session
    return Session(self.env, req)   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/session.py", line 157, in __init__
    self.get_session(sid)   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/session.py", line 178, in get_session
    super(Session, self).get开发者_如何学运维_session(sid, authenticated)  File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/web/session.py", line 59, in get_session
    (sid, int(authenticated)))   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/db/util.py", line 64, in execute
    return self.cursor.execute(sql_escape_percent(sql), args)   File "/usr/local/lib/python2.6/dist-packages/Trac-0.11.7-py2.6.egg/trac/db/util.py", line 64, in execute
    return self.cursor.execute(sql_escape_percent(sql), args) InternalError: current transaction is aborted, commands ignored until end of transaction block

You installed Trac 0.12? Your traceback shows "Trac-0.11.7-py2.6.egg". Looks like you need to do some cleanup.