MacBook App Store not downloading or updating apps

When I want to download an app (clicking on the cloud with arrow icon) or when I want to update an app (like XCode), the app gets the "square in circle" icon and stays like this forever. - clicking on the square does not stop/cancel the process - signing out and back in the App Store or restarting the MacBook (Big Sur) did not help (i.e. the same behaviour when signing back in or after restart. - there is Internet (since I see and choose App Store content) Is there a command line (in the terminal) to force cancel a started download / update? Is there a place (log file or already installed logging app) to see the errors why App Store is stuck?