I can confirm the problem. Downloading any files from the Mattermost desktop app to my Mac fails since just recently.
The download fails immediately with a red “cancelled” warning. Clicking on the three dots on the right in the ‘Downloads’ popup and then clicking on “Show in Finder” opens an error message: “Mattermost has no permissions for opening ‘Downloads’”.
I changed the default download location, but without any luck…
The folder permissions are definitely fine and downloading the same file to the same location using the web browser works without a problem.
I could resolve the problem by uninstalling and re-installing the app, but now the same problem just appeared again… which is quite annoying.
I’d appreciate any kind of help!
PS. I’d liked to append screenshots, but uploading them here continuously fails with the message “Sorry, there was an error uploading that file. Please try again.”