Review for Provider for Google Calendar by Firefox user d2a2bc
Rated 5 out of 5 stars
I absolutely disagree with the obsolete statement!
As stated by other advanced users: the stock implementation of thunderbird does NOT support shared private google calendars.
EDIT: Philip Kewisch commented the current issue on his twitter: error should be gone in a few days. See: https://twitter.com/pkewisch/status/1485690970624643074?cxt=HHwWhMCy4Z6Enp4pAAAA
EDIT2: my error disapeared.
To create your own collections, you must have a Mozilla Add-ons account.