Synchronization: Appointment cannot be saved: Forbidden

If you have set up a synchronization to iCloud, Google or other calendar and you get the error message Unable to save appointment: Forbidden, it may be due to the following reasons:

1. eTermin does not have write permission to write to your calendars. Make sure that the permission has been granted in the account settings.

2. The password has been changed or is invalid. Please enter the correct password in Company > Synchronization.