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FRITZ!Box reports "Authentication error occurred" when using Google calendar

The error message "Authentication error occurred" is displayed for the Google calendar on the tab "Switch Automatically" in the FRITZ!Box user interface by the profile of the smart plug, for example FRITZ!DECT 200.


  • The FRITZ!Box's access rights to the calendar were removed in the Google account.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Box.

1 Deleting a calendar

Before requesting access to the calendar again, you must first delete all of the Google calendars in the FRITZ!Box:

  1. Click "Home Network" in the FRITZ!Box user interface.
  2. Click "Smart Home" in the "Home Network" menu.
  3. Click the (Switch Automatically) button next to the respective device or any smart home device that belongs to the group.
  4. Click the link "Remove connections from Google calendar".
  5. Click the "Reset Google Calendar" button.
  6. Click "OK" when you are asked whether you want to delete all Google calendars from the FRITZ!Box.

2 Adding a calendar