FRITZ!Box 6840 LTE Service - Knowledge Base

FRITZ!Box 6840 LTE Service

FRITZ!Box reports "Internal system error (17) occurred" when adding a Google calendar

When setting up automatic switching for a smart home device, FRITZ!DECT, or a FRITZ!Powerline adapter, you cannot add a Google calendar. During the authentication process, the error message "The authentication process for the Google Calendar on the FRITZ!Box could not complete the procedure successfully. Internal system error (17) occurred" is displayed.


  • You did not set up or did not correctly set up the Google calendar, the name of the calendar contains illegal characters, or it is misspelled.

1 Creating a calendar

The following step is only necessary if you have not created a Google calendar yet:

2 Correcting the name of calendar and adding it

The following step is only necessary if you have already created a Google calendar:

Correcting the name of calendar

  1. Log into your Google account.
  2. Rename the calendar you want to use for the smart home device: Remove all special characters, spaces, letters with umlauts, or accented letters from the calendar's name. The name may only contain standard alphanumeric characters.

Adding a calendar

  1. Add the Google calendar for the smart home device.