We have a user on our server that has been removed from all teams (for testing). I can still see my 1 to 1 chat with him on the left chat menu (listed as outside of team), but the whenever I message him, it crashes the mattermost service. Has anyone seen this before? Not sure if it matters, but the user is a System Administrator.
Thanks @marcchang for the report,
This is in fact a bug and we should have a fix for it in our January release.
You can find the original bug report here: https://mattermost.atlassian.net/browse/PLT-4636