I'm working on setting up a server running Plesk 10.4.4 Update #13 on Centos 6.2. I've configured Mailman and now I want to set up some mailing lists. I've created a list in the Plesk control panel, but when I try to administer the new list (by visiting http://lists.[domain].com/mailman/admin/[listname] I see the following error: Bug in Mailman version 2.1.12 We're sorry, we hit a bug! Please inform the webmaster for this site of this problem. Printing of traceback and other system information has been explicitly inhibited, but the webmaster can find this information in the Mailman error logs. I see exactly the same error if I try to go to the list info page at http://lists.[domain].com/mailman/listinfo/[listname]. I would follow the instructions and look in the error logs, but I can't find them. I would expect to find a file at /var/log/mailman/error, but there's nothing there. Has anyone else seen this? Any suggestions for tracking down and fixing the problem? Cheers, Dave... p.s. Just one other piece of information - my test list seems to work correctly. It sends all the expected email. It's just the web pages for the list that seem to be broken. Update: I got to the bottom of this, so I'm documenting the answer in case anyone else has the same problem. The fact that I couldn't find the error log was the clue. The problem was that the Mailman process didn't have permissions to create an error log. And it seems that if Mailman can't create an error log then it will respond to any web request with this error page. Creating an error log file (in /var/log/mailman/error) and giving it the correct permissions fixed the problem.