Lightning in Thunderbird works fine with my own Google calendar. On Google I also have read access to my wife's calendar and a public (holidays) calendar, which were both subscribed to in Lightning. Recently both of these calendars have come up empty in Lightning, even though I can still see them in Google. I therefore tried to unsubscribe and resubscribe to them in Lightning. [https://support.mozilla.org/en-US/kb/creating-new-calendars#w_on-the-network-connect-to-your-online-calendars This] appears to be out of date. The illustration doesn't look like what I see in Google. Nonetheless, by improvising on those instructions, I was able to restore the public (holidays) calendar in Lightning. However, this doesn't work for my wife's calendar. As long as I am logged in to my Google account the URL provided by Google works in Firefox, but no data from her calendar are displayed in Lightning, even though I provided my Google login credentials. Other calendar apps (Apple calendars in iPadOS and MacOS and Outlook calendar in Windows 10) can see her calendar, How can I restore (read-only) access in Lightning?