You have to right-click a calendar in the left pane of the calendar tab, Properties, and check to enable. As for the Provider add-on, work is underway on a version for TB 78:

https://github.com/kewisch/gdata-provider/issues/77#issuecomment-659069009

You could also try TbSync 2.16 to sync Google calendars and contacts, plus other providers, in TB 78:

https://addons.thunderbird.net/en-us/thunderbird/addon/tbsync/versions/?page=1#version-2.16

You have to right-click a calendar in the left pane of the calendar tab, Properties, and check to enable.

Thanks for the tips. Right clicking on any calendar opens up its menu but clicking on the Enable box has no effect, as in it clicking on it doesn't show a check mark or an X in it that shows it's been enabled.

The Enable checkbox works here, at least with a local calendar (see picture). This is with TB 78 and a profile created with 78. Was your profile previously used with TB 68? Many upgrade issues have appeared by running 78 on an older-version profile. If it's network calendar that relies on an incompatible or missing add-on, it might not be possible to enable the calendar.

Enable checkbox works here too with local calendar. My profile has been used with every previous version of TB for many years, and this is the first time this happens.

Thanks for the heads up on work being done to update Provider. I installed TBSync but for whatever reason I'm missing where this add-on settings can be changed. I checked every settings screen already.

It's under Tools (see picture). Press Alt if the Menu Bar with Tools is hidden.

It's under Tools (see picture). Press Alt if the Menu Bar with Tools is hidden.

Using the TOOLS option in the hamburger menu wasn't it then, dang! Thanks for all your help, as of now only the Contacts calendar is the only one that hasn't updated yet. But all others did! Thanks!!!!!!!!!

What MORON decided to update tbird and exclude all the calendars? Typical dipshit tech nerd who does not live in a real world where calendars are important. Why bother with this shit that takes days to fix, how about you actually produce a product that works, the way it did before you fucked it up with an update.

You can tell this is not an organization that depends on actually selling a product. You do not give a shit about the consumer of your product. Next comes the we only develop the main product, but the fact that consumers rely on those add ons means nothing to you. NO wonder this product is at the bottom of the shit pile when it comes to a reliable quality product.

You will never get a dime from me, your product is worth what I have paid for it so far.

It's under Tools (see picture). Press Alt if the Menu Bar with Tools is hidden.

I tried clicking this Synchronization settings option after installing TBsync. Nothing popped-up at first but after restart, it worked. Finally, I have one of many calendars in working condition.

I don't even have the Add-on options button under Tools. I wonder if that is normal.

How can I upgrade my TB68 profile which I am now using with 78? Why TB didn't do it automatically? I have spent the last 6 hours looking for a solution to my calendar problem. After this I need to find a solution to make the "Conversations" add-on work properly without slowing down TB.

Updates are meant to make life easy, not hard :(

Hi All,

I had this problem today with last update. My personal Synology server have an auto-signed certificate that you must add into certificates bank of Thunderbird (translate from French : Options/ADVANCED/Certificates/manage certificates and Add an exception). Ex. https://mon.example.fr:5111

In fact, self-signed certificates confirmed via the popup dialog box that opens when Thunderbird's "Confirm Security Exception" calendar request is opened do not work.

The addition of certificates by this way solved the issues.

My calendar issue is similar after updating to v78. I didn't notice what the previous version was, but I update whenever a new one is available. After the update, the existing 3 network calendars were disabled, and I could not enable them. I copied the location from the properties tab for each calendar, then unsubscribed from all 3, I tried adding new calendars using the saved location, but the indicated locations were not URLs (they were in some idiosyncratic format), so that didn't work.

I use the same 3 calendars in Google Calendar, so I found the URL for each one there, then created new calendars in Thunderbird. Everything seemed OK, but events for only one of the three calendars are displayed. All 3 were created the same way, and all 3 say they are enabled. One of the calendars is my Google calendar, one is a public calendar of US Holidays, and the third is a public calendar of Jewish Holidays. Only events from the Jewish calendar are displayed.

I tried "synchronize", then restarted Thunderbird, but no joy. What else can I try?

Get Mailbird, it actually works with Google Calendar. Easy to set up very few hassles like this amateur shit show.

I found that the "Provider for Google Calendar" extension had not automatically updated, although it was set to automatically update. After updating, my private Google calendar events appeared. But the US Holidays calendar still does not display any holidays.

I have tried everything suggested above, excluding the Synchronization Settings in the Tools menu, because it doesn't exist on my Tools menu, but still my entire TB calendar is missing and even though I clicked the Enable pill (not a checkbox as stated earlier) beside each calendars, all my calendars are missing ANY events, past and future. This totally sucks.

I was using a public US Holidays calendar, which I never got to work with TB v78. I searched for another public calendar site, and the new one works.

Adding Provider for Google calendar restored all of my calendars, including a local one that had disappeared and the Holidays in the United States.