@robi Didn't know there was one. I'm guessing it's an Electron wrapper like almost every other "app" nowadays? In which case, I already roll my own with WebCatalog for the extra features.

Thank you, that works. But why I cant upload plugins via GUI although I have set the right setting (https://screenshots.x-mailer.de/u/smichna-2020.09.15-1TsnjG54.png).

@katarina You can use the mattermost CLI tool to export from your existing installation and then import to Cloudron installation. I have added the instructions to our docs here - https://cloudron.io/documentation/apps/mattermost/#migration

ahh, thanks very much! that makes sense