Hi @abkrimm ,
can you also reproduce that using a web browser and by accessing the server directly and not via the desktop app?
If so, what does the URL look like after you clicked on any of your classmates?
Did this start happening recently and if so, where there any changes lately to your setup? Any updates you installed or the like?
What mattermost server version are you running at the moment and if you upgraded, which version did you run prior to upgrading?
Can you see anything relevant in the server’s logfiles (/opt/mattermost/logs/mattermost.log by default) if you have access to them?