Error 422 when setting up graph

Infos:

  • Used Zammad version: 6.5.2
  • Used Zammad installation type: source
  • Operating system: Ubuntu 24.04.3 LTS
  • Browser + version: Firefox 147.0.1

I wanted to link my support email address with Graph to Zammad today. I created the app in the admin center according to the instructions. However, when I try to add an account under Microsoft 365 Graph Email in Zammad, I receive the following error message after logging in to the Microsoft website:

I have no idea what’s wrong. Does anyone have any ideas?