“The room has been destroyed for an unknown reason”
I’‘m getting this error often recently. It happens when one of new Room Options is disabled (changing nickname, registered nicknames only, …). So if i try to change nickname in room i’'m thrown out. Not good.
The XML packets look fine (ie. as expected). The 406 not-acceptable error code is what JM is returning when a user tries to change his nickname and that feature is disabled.
In particular, the spec does not mention that a server may reject changing a nickname so I would say that each client will show a different kind of error or just continue as if the rename was done.