Gajim doesn't handle MUC errors
Gajim only handles (legacy?) error codes coming from a MUC. Errors currently documented in XEP-0045 <http://xmpp.org/extensions/xep-0045.html> e.g.
\<presence
from='darkcave@chat.shakespeare.lit'
to='hag66@shakespeare.lit/pda'
type='error'>
\<x xmlns='http://jabber.org/protocol/muc'/>
\<error type='cancel'>
\<conflict xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
\</error>
\</presence>
are not handle. This currently causes problems in conjunction with Prosody. It will also be fixed there, but should obviously be fixed in Gajim too.