I finally found the time to make my errbot plugin errbot-exec compatible with errbot version 5 and Python 3, so I can finally use it again on Debian 9.
SSL error
When starting errbot, I got a connection error:
$ /usr/local/bin/errbot --config=/etc/errbot/bookmarks.py ... 22:23:52 ERROR sleekxmpp.xmlstream.xmlst CERT: Invalid certificate trust chain. 22:23:52 ERROR sleekxmpp.xmlstream.xmlst Can not read from closed socket.
After enabling debug logging in the config file, I got more information:
22:23:53 DEBUG sleekxmpp.features.featur Starting TLS 22:23:53 INFO sleekxmpp.xmlstream.xmlst Negotiating TLS 22:23:53 INFO sleekxmpp.xmlstream.xmlst Using SSL version: TLSv1 22:23:53 ERROR sleekxmpp.xmlstream.xmlst CERT: Invalid certificate trust chain.
Then I used the XMPP observatory to get information about my own server's SSL configuration.. and saw:
TLSv1 No TLSv1.1 Yes TLSv1.2 Yes
I suspected that sleekxmpp tried to connect with TLS v1.0 and failed because of that.
After enabling TLSv1.0 in ejabberd.yml, errbot could connect without problems.