FRITZ!Box 7490 Service - Knowledge Base

FRITZ!Box 7490 Service

Error message: "Authentication error occurred." when using Google calendar

The error message "Authentication error occurred." is displayed for the Google calendar in the profile of your smart home device on the tab "Switch Automatically" in the FRITZ!Box user interface.


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

Note:The configuration procedure and notes on functions given in this guide refer to the latest FRITZ!OS for your FRITZ!Box.

1 Deleting a calendar

In order to request access rights for 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. If available, select the option "All smart home devices" in the drop-down list "viewing".
  4. Click the button (Edit) for the relevant device.
  5. Click on the "Switch automatically" tab.
  6. Click on the link "Remove connections from Google calendar".
  7. Click the button "Reset Google Calendar".
  8. Confirm the question about whether you would like to delete all Google calendars from the FRITZ!Box with "OK".

Now all Google calendars are deleted and all smart home devices that use a Google calendar are set to manual switching.

2 Adding a calendar