re: There are new Enable buttons on the left for the various potential sources of events for the calendar, but clicking on any of them has no effect in what is displayed in the calendar grid. Can you please post image(s) showing what you are seeing.

There are new 'enable' buttons on left adjacent to calendar eg: Home, but I believe that enables the relevant calendar.

re :I was on vers 78.12.0 and Thunderbird told me a new version was available.

If you have Thunderbird installing updates and not an updater software doing it, then you would have been updated to version 78.13.0

Thunderbird is not updating to the 91* version at the moment as per information at the download webpage: Thunderbird 91 is only offered as direct download from thunderbird.net and not as an upgrade from Thunderbird version 78 or earlier. https://www.thunderbird.net/en-US/thunderbird/91.0.1/releasenotes/

re: but I get an error message that the existing profile has been updated for the newer version, and that If I want to use the old version, I need to create a new profile and reload all my accounts, add-ins, etc. Wait, what?

It has been like that since version 68*. Create a backup copy of your profile (exit Thunderbird and then get a copy of the 'Thunderbird' folder which is in the 'Roaming' folder - see images as guide) and put into a folder called 'TB-91' so you know what version used it. Then at least you can go back to it if required. Use info in link -section 'What happens to my profile if I downgrade to a previous version of Thunderbird?' https://support.mozilla.org/en-US/kb/dedicated-profile-thunderbird-installation Basically after installing program do not allow Thunderbird to start automatically. You need to start it using the 'Run app' using : thunderbird.exe -p --allow-downgrade i'm not sure what would happen to the address books as there have been loads of changes yet again.

re: Why was the old profile not preserved and a new one created for the new version to allow for reverting back from a bad update? I can only assume you did not create a backup before you decided to install version 91.0.1

I'm trying to find out whether people are getting problems because they allowed other updater software to update Thunderbird to 91.0.1 OR did people deliberately choose to uninstall 78* and then download and install 91*

Can you tell me whether it was a deliberate uninstall and reinstall or you allowed updater software to update to 91* ?

As I said, I am never able to update TB from within TB, so I went to the TB website because I thought that was the most reliable up-to-date version of TB that is available. After downloading, I installed vers 91 on top of vers 78 without doing an uninstall.

I cannot find where I can manually download 78.13. I could not find a link on the website. The only link that is there does a download of 91. If 91 is that flaky, then that version should not be available for casual users to download from the main TB page.

No, I did not manually do a backup. That should be a function of what TB should do when doing an update. Or, at least, popup a message telling people that need to manually do a backup.

I do not have an image of the blank calendar grid. It is blank with no calendar events populated from my Gmail account.

See https://support.mozilla.org/en-US/questions/1347790#answer-1436712

I have just started using a new laptop, installing TB 91 from the website and moving my profile (by copying it into the new default profile folder; I have done this before without any trouble). TB shows all of my stored emails and incoming emails correctly but the calendar is empty.

I do not use any sort of syncing with Google; I just keep all my appointments in TB.

I tried the restore procedure using ConfigEd; there is nothing there.

I tried uninstalling and reinstalling to no avail.

I need the 10 years of calendar events in my profile and the events that are in there for the next year. I am not a computer-savvy person at all. Help, please!

As per link as advised by sfhowes : There are many users reporting the calendar is missing after the update. If you were using the Provider add-on, disable or remove it, then add the calendar directly as a CalDAV calendar:

• https://support.mozilla.org/en-US/questions/1304356#answer-1368791
• https://github.com/kewisch/gdata-provider/issues/194

Alternative which has worked for another person:

• reinstall 78 to another directory, retrieve the profile form backup to another dir.

http://ftp.mozilla.org/pub/thunderbird/releases/78.13.0/ Choose relevant OS, then choose language and then download file and choose where to install.

• Point TB 78 to the new location, export the calendar and then import it to 91.

https://support.mozilla.org/en-US/questions/1347467?utm_campaign=questions-reply&utm_source=notification&utm_medium=email#answer-1437383

I tried reinstalling 78 to a different directory and then restoring a profile from a backup drive to that directory. It did not work, as it appears that the backup profile being copied onto the laptop today is interpreted as having been altered by a newer version of TB and 78 will not load it.

There does not appear to be a way to point the Profile Manager to the backup drive itself. I am going to try to create a new profile in 78's Profile Manager on the backup external drive and see if I can then change the actual backup profile's name to the new one as a workaround.

It is unbelievable that there was no warning in the 91 upgrade that this could happen. I upgraded from inside TB, not from going to the website. If there are this many changes and things that are not backwards compatible and lose years of data, the upgrade advisory in TB should actually point to the website with copious warnings.

I tried creating a new Profile on the backup external drive and then changing the actual backup to the new profile's name; it did not work.

In what file(s) is the calendar data stored? Is there any way to get just those files and import them to 91?

I dug around in the support forums some more and finally figured out how to get my calendar from the backup (78) to 91. This is the procedure that worked for me:

1) Installed TB78 in a different directory. Created a new profile and added one item to its calendar in a dummy calendar. Closed TB 78.

2) Went to my backup folder, and copied the calendar-data folder and prefs.js to the new 78 profile. Opened 78 and the calendar was there.

3) Exported the calendar as Outlook csv. Opened it in Libre Office.

4) Opened TB 91 and exported the dummy calendar as Outlook csv. Opened it in Libre Office. Compared the two and saw that their layout was identical. Closed them both.

5) In TB 91 in the Calendar tab, went to the dropdown menu that is just above the Month tab, chose Events and Tasks, then Import. Navigated to the folder where the 78 exported calendar is, changed the file type to csv, then when the exported calendar appeared, chose a destination calendar and clicked Open.

6) Every event and its details/notes imported correctly. (I do not use Tasks.)

I am missing about two weeks' worth of details as my previous TB profile backup was about two weeks before the upgrade, but having all the events and their notes back to December 2013 was a relief. I wish I had not had to spend four hours of digging around for something that should have been addressed and, if not anticipated, had a comprehensive workaround published quickly.

I hope this helps.

Thanks, alternatives are always useful.

My solution (posted on Mozillazine.org) was similar but no new profile required.

Update...

i managed to get a complete restore on my ver 78.X profile, reinstalled 78.x, pointed it to the right profile location... and the calendar was there.. I exported it.

First attempt to overwrite the "Home" calendar failed in ver 90.0 ... I left it running for a bit less than an hr, no action, no error message. I killed TB as I could not close the window...

Restarted TB 90, deleted the home calendar and used another that I had created as a test (empty). The calendar is alive and appears well.

It looks to me like there are big problems with calendar conversion from v78 to 90....

Aside, it should be possible to create a new calendar as part of an import rather than have to use an existing calendar...

Thanks to all for your help.

Hopefully the TB dev team is addressing this.

Richard

I have reported the calendar issues as a bug report: Bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=1727062

Thanks Toad-Hall. Took a look, hope the internal calendar side does not get swamped by google (external) calendar issues. Richard