Simon Handfield via Mailman-users writes:
I have been working through other threads that indicate the same symptom (500 error when loading held_messages for a list).
You want threads that deal with Unicode:
Error reported in log with debug enabled:
Traceback (most recent call last):
And that last call is::
File "/usr/lib/python3.6/email/message.py", line 315, in set_payload payload = payload.encode(charset.output_charset) UnicodeEncodeError: 'ascii' codec can't encode characters in position 8-9: ordinal not in range(128)
It appears that the message is improperly constructed, and either a Content-Type field has a omitted or inappropriate charset parameter, or perhaps the Content-Type field is omitted entirely (ASCII is the default charset).
This is frequently a problem created by spam messages.
The message should be in the shunt queue. You can examine it with the command "mailman qfile /path/to/message_file.pck". Unfortunately it's not clear from the backtrace where in the message this is: it's at the beginning of a part ("position 8-9") or maybe line, but the part could be late in the message.
If it's spam, you can just delete the file (and do whatever else you do about spam, of course). If it's not spam, it would help if you can guess what language and charset are being used in the message, and we can go from there.
If this is unclear, feel free to ask more.