Please check that you have enabled the home calendar.

If still fails - try this - create a new local calendar, enable it and then add some events to test.

You mention 'main' calendar but what is the 'main' calendar?

Are you talking about the default 'Home' local Thunderbird calendar or one you hook up to like Google ?

Do you use any addons to link to calendar like Provider for Google ? If this is a gmail/google calendar then make sure you are using the up to date addon: https://addons.thunderbird.net/en-GB/thunderbird/addon/provider-for-google-calendar/

Also what OS are you using?

It was enabled. Curiously, when I opened properties I noticed that a couple of things were missing. The main thing missing was the panel showing were the location of the data file. To me, that is why the calendar would be empty and unusable. I created a new calendar and it also suffered the same problem.

The 'main' calendar is as you suggest, the 'Home' local Thunderbird calendar. I did have Provider for Google but disabled it to see if it solved the problem (it didn't).

The OS is Windows 10 21H1

Curiously, when I opened properties I noticed that a couple of things were missing. The main thing missing was the panel showing were the location of the data file. To me, that is why the calendar would be empty and unusable. I created a new calendar and it also suffered the same problem.

There is no such "panel" for a local calendar. See attached image.

Can you check this for me. Menu app icon > Tools > Developer Tools > click on 'Error console'

Make the window as large as possible so as much info is displayed as possible. take a screenshot, save as jpeg image. Repeat the process if you cannot display it all in one go. Post the jpeg images in this forum question. The information may contain something useful for the developers. I'm looking for anything relating to calendar.

re : I did have Provider for Google but disabled it Are you saying you have a google calendar which you use in Thunderbird? If yes, does it work ok? If no I don't have a google calendar, or yes I have a google calendar but it does not work - please remove the 'Provider for Google Calendar' addon.

When addon has been removed - start Thunderbird. Then create a new Home Calendar, enable it and check to see if it retains events etc.

Once this is working you can then download/install the most up to date 'Provider for Google Calendar' addon - but only if it is required.

Hi Toad-hall, hopefully this is of use to someone.

Thanks for info. It would be helpful if you could check whether the files still contain data, so we can find out whether this is a display issue or not. Or whether the backup has data files that can be used to get calendar back to old settings.

This is where the files are located, so please provide images showing the following. Menu app icon > Help > Troubleshooting Information Under 'Application Basics' - about 8th in list is Profile Folder - Click on 'Open folder' A new window opens showing the contents of your 'profile name' folder.

Click on 'calendar-data' folder to see contents. Make sure it is showing details so these column headers - Name, Date Modified, Type, Size Post an image

There should also be a 'backup' folder Click on the 'backup' folder to see contents Make sure it is showing details so these column headers - Name, Date Modified, Type, Size Post an image

I had a look in the 'calendar-data' and all that was there was the 'backup' folder and three SQLITE files named cache, deleted and local . The Backup folder only contained a number of backups of calendar entries made after the upgrade of Thunderbird. This leads me to believe that all of the older data is lost!

I had a look in the 'calendar-data' and all that was there was the 'backup' folder and three SQLITE files named cache, deleted and local .

This is what is currently being used, so if your files show a good size but you do not see anything then it could be a display issue. Hence why I need the images.

Please make sure the following column headers are shown. 'Name', 'Date Modified', 'Type', 'Size', 'Date Created'

The Backup folder only contained a number of backups of calendar entries made after the upgrade of Thunderbird. This leads me to believe that all of the older data is lost!

I need an image showing the information. Please make sure the following column headers are shown because Creation date is not the same as modified date. 'Name', 'Date Modified', 'Type', 'Size', 'Date Created'

Have you updated version 91 a couple of times as updates occur?

Menu app icon > Preferences > General scroll down to 'Updates' section click on 'show update history'

post an image showing the history contents.

All this information is important because developers need to see factual info to help work out what is going on.

I tried to create the same issue, but when I uninstalled 78* and then installed 91.0.3 everything worked, so my data only shows what happens when all is good.

I am currently using version 92 and nothing has changed. This comment still applies: "I had a look in the 'calendar-data' and all that was there was the 'backup' folder and three SQLITE files named cache, deleted and local . The Backup folder only contained a number of backups of calendar entries made after the upgrade of Thunderbird. This leads me to believe that all of the older data is lost!"

Is there a reason why you are not posting images showing requested information ? Are you saying all the files in the calendar-data/backup folder show identical time and date for both 'Date Modified' and 'Date Created' column headers ? I've tried to get you to show me this information because it is important.

Please try the following to see if this has a desired result. As you currently do not have contents displaying in the Home default calendar you have nothing to lose by attempting the following.

Exit Thunderbird now - this is important.

Access your profile name folder click to open calendar-data/backup folder You will see files like this: 'local.v22.sqlite' Copy that 'local.v22.sqlite' file

Go up directory to the 'calendar-data' folder where you will see 'local.sqlite' file Paste the 'local.v22.sqlite' into 'calendar-data' folder

Edit/rename the name of the 'local.sqlite' file so it looks like this 'local.sqlite.bak' Edit/rename the name of the 'local.v22.sqlite' file so it says 'local.sqlite'

Start Thunderbird

Check the Calendar and report back on results.

Installed update 91.2.0 - all events disappeared. And Lightening didn't work either. Removed lightening. Did tests with new events to trigger daily. They'll show fine. Close and restart Thunderbird, all events gone. Did this several times with and without Lightening. .

Did as you said copying the file local.v22.sqlite. Opened TB, did an event triggering in 10min. Closed TB. Opened TB, event gone. BTW the .sqlite is 6,144KB long if that indicates data is in there as opposed to nothing. Note: Lightening app not installed but when it was, has the same issue.

thanks,

Update on info - the following has worked for others.

Try this:

• Menu app icon > Help > Troubleshooting Information
• Under 'Application Basics' - about 11th in list is Profile Folder - Click on 'Open folder'

A new window opens showing the contents of your 'profile name' folder.

• Exit Thunderbird if running....this is important

• Click on 'calendar-data' folder to see contents.
• Copy local.sqlite file and put copy onto desktop.
• In calendar-data folder - Rename 'local.sqlite' to 'local.sqlite.bak' - but if you have already done this using previous instructions then delete the 'local.sqlite' file.

Download install addon - Firefox sqlite DB manager add-on into Firefox browser.

• https://addons.mozilla.org/en-GB/firefox/addon/sqlite-manager-webext/

• Start the addon - you should see a new icon on the toolbar near the menu app icon - hover over icon and it will say SQLite Manager - clickon it.

Use addon to open the desktop copy of the local.sqlite DB

• drag the desktop copy of 'local.sqlite' over to browser and drop into the opened addon.

run two SQL queries - you type this in the yellow area

Searched for items with null id: SELECT * from cal_events WHERE id IS NULL LIMIT 100

If you find any... So then use the following to deleted it: DELETE FROM cal_events WHERE id IS NULL

• Saved the database file, 'Save' located at the bottom - save is usually saved in the 'Downloads' folder.

• Access the 'Downloads' folder to locate downloaded saved version of 'local.sqlite'.
• put the saved 'local.sqlite' back into the 'calendar-data' folder - that is the copy in the Downloads folder and not the copy you originally put on desktop.

restart Thunderbird and report on results.

I give up. Where is this "menu"? And the "app icon"? (I'm using Win 10 if that matters) I searched for Lightening just now, and it's removed from extensions. I did the *.bak routine you suggested a day or two ago, and didn't change anything Thanks, I'll wait for a TB fix.

Update on info - the following has worked for others. Try this:

• Menu app icon > Help > Troubleshooting Information
• Under 'Application Basics' - about 11th in list is Profile Folder - Click on 'Open folder'

A new window opens showing the contents of your 'profile name' folder.

• Exit Thunderbird if running....this is important

• Click on 'calendar-data' folder to see contents.
• Copy local.sqlite file and put copy onto desktop.
• In calendar-data folder - Rename 'local.sqlite' to 'local.sqlite.bak' - but if you have already done this using previous instructions then delete the 'local.sqlite' file.

Download install addon - Firefox sqlite DB manager add-on into Firefox browser.

• https://addons.mozilla.org/en-GB/firefox/addon/sqlite-manager-webext/

• Start the addon - you should see a new icon on the toolbar near the menu app icon - hover over icon and it will say SQLite Manager - clickon it.

Use addon to open the desktop copy of the local.sqlite DB

• drag the desktop copy of 'local.sqlite' over to browser and drop into the opened addon.

run two SQL queries - you type this in the yellow area Searched for items with null id: SELECT * from cal_events WHERE id IS NULL LIMIT 100 If you find any... So then use the following to deleted it: DELETE FROM cal_events WHERE id IS NULL

• Saved the database file, 'Save' located at the bottom - save is usually saved in the 'Downloads' folder.

• Access the 'Downloads' folder to locate downloaded saved version of 'local.sqlite'.
• put the saved 'local.sqlite' back into the 'calendar-data' folder - that is the copy in the Downloads folder and not the copy you originally put on desktop.

restart Thunderbird and report on results.

I performed the tasks that you recommended and nothing has changed at all.

Run the query

SELECT * from "cal_events" LIMIT 10

and see if any events are listed in the output.

And Lightening didn't work either. Removed lightening. .....I give up. Where is this "menu"? And the "app icon"? (I'm using Win 10 if that matters) I searched for Lightening just now, and it's removed from extensions. I did the *.bak routine you suggested a day or two ago, and didn't change anything Thanks, I'll wait for a TB fix.

The 'menu app icon' is on the right side (by default - but you can move it to the left if desired) and it has 3 horizontal lines.

Lightning is no longer an extension. It is fully integrated. It's been that way for several versions. So it does not appear in the 'Addons' extension list. Calendar is opened in a new tab by clicking on the Calendar icon. Please explain what you mean by 'Removed Lightning'. What did you do to remove it? Are you using version 91.2.1 ? That is the current version.