resolved a socalled mailman-bug

Many many times I faced the following page when I tried to do something on my mailman-installation:

Bug in Mailman version 2.1.9

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 hate this kind of message, cause it makes you think of some big stuff when in reality the problem is rather small. So small actually that you might spend hours to find it cause no proper error-message is given.

So I start this page by today to list all the possible sources for this misleading error-message. So I dont have to start all over again every time.


As far as I can remember the source for this “bug” was always a wrong permission, a wrong/missing symlink or a missing file. Some kind of I/O-error thats no trapped by mailman in a a proper way with a proper errormessage.

Looking in the mailman-log-files (/var/lib/mailman/logs/error on my ubuntu) is a good start and especially the traceback-section.