Update 12.04.2024: I was informed by phone today that a hotfix for the login problems was rolled out on 11.04.2024. Logging in should now be possible again after reinstalling the app.
If it still does not work, here is a possible solution with which you can log in via QR code.
1. open our WebUntis page via the browser of another device (e.g. on a PC). DIRECTLY TO WEBUNTIS
2. log in there with your data. (The user name is your e-mail address)
3. you should see a dot with your name at the bottom left above the "Log out" item. Use this to open your profile.
4. click on the "Approvals" item at the top. In the window that opens, you can display your personal login QR code using the "Display" button.
5. select the QR code as the login method in the Untis app and scan it.
If you need new login data, please write an e-mail to Mr. Tarp(tarpsa@egs.gronau.de) who will be happy to reset your password.