Cannot join mattermost channels

[truenicoco]

Using purple-mattermost, channels are properly listed in gajim GUI, but joining one results in an empty channel that doesn't seem linked to the actual mattermost channel.
Since it works fine with finch, something may be wrong on the spectrum2 side?

Here is what backend.log shows:

7987: 2020-04-06 19:04:31,542 INFO  libpurple: mattermost:Got response: {"id":"api.context.404.app_error","message":"Désolé, impossible de trouver cette page.","detailed_error":"There doesn't appear to be an api call for the url='/api/v4/users/username/REDACTEDID^REDACTEDCHANNELNAME---REDACTEDTEAMNAME'.  Typo? are you missing a team_id or user_id as part of the url?","status_code":404}

I also reported this on purple-mattermost issues: EionRobb/purple-mattermost#60 (comment)

[truenicoco]

Trying to investigate this a bit further, I found these errors might also be relevant in the logs.

When trying to send a typing notification to the chatroom:

8949: 2020-04-16 08:17:51,523 INFO  backend: nicoco@nicoco.fr: sending typing notify to REDACTEDID^REDACTEDCHANNELNAME---REDACTEDTEAMNAME
8949: 2020-04-16 08:17:51,523 ERROR backend: g_log mm_conv_send_typing: assertion 'room_id' failed

When actually sending the message (I think…):

8949: 2020-04-16 08:17:56,944 INFO  libpurple: mattermost:Got response: {"id":"store.sql_user.get_by_username.app_error","message":"Impossible de trouver un compte existant correspondant à votre nom d'utilisateur pour cette équipe. Cette équipe nécessite peut-être une invitation de la part du propriétaire pour pouvoir la rejoindre.","detailed_error":"","request_id":"sxcbj35q578wbpyno49q577uhr","status_code":404}
8949: 2020-04-16 08:17:56,945 ERROR backend: g_log purple_conversation_get_im_data: assertion 'conv != NULL' failed

The error message translates to "no existing account with your username in this team. you may need an invite", but I can send message to this team/channel using finch (or the official mattermost client, obviously)

Also, but this only happened once, I received a roster add request from the channel after sending a message. So there seem to be a confusion between groupchats and single user with this plugin.

[camlafit]

Hello

I try to use also this plugin but I get only user on my roster, any muc are listed. How are you config you're server to get muc listing ?