Mac OS X Server 10.3: "We hit a bug" message appears when creating a mailing list

This Mailman interface is available at http://myserver.com/mailman/admin, where "myserver.com" would be replaced with the address of your server.

When you try to save a new mailing list, you see this message:

Bug in Mailman version 2.1.2

We're sorry, we hit a bug!

If you would like to help us identify the problem, please email a copy of this page to the webmaster for this site with a description of what happened. Thanks!

This message is followed by a detailed traceback.

To resolve the issue, follow these steps:

1. Open Terminal (/Applications/Utilities/).
2. Type: sudo chmod g+w /var/mailman/data/aliases.db
3. Press Return.
4. Use Server Admin to remove the partially created list.