Been getting this synchronisation error all day and none of my calendars are syncing. Not sure which account is affected.

The full error log is really extensive, let me know if you need the full thing.

Error:

Service unavailable (503).

Response status code does not indicate success: 503 (Service Unavailable).

CalendarApp.ProviderBase.Exceptions.AccountRequestException: Service unavailable (503).

Response status code does not indicate success: 503 (Service Unavailable). ---> CalendarApp.Common.Net.HttpException: Service unavailable (503).

Response status code does not indicate success: 503 (Service Unavailable). ---> System.Exception: Service unavailable (503).