Should I uninstall 115 before installing 102? Will all my accounts and settings survive? Is there some backup that will preserve "everything"?

Yes, uninstall 115 first. To use this, you must first have had System Restore turned on, or there will be no backups to reload. You select the restore point you want. It only restores your system files and programs. Your data is not affected.

What worked for me on linux (Ubuntu) to go back to 102.15 AFTER 115 Update had already changed the profile:

0. BackUp your profile-Folder(s)

1. Download from https://ftp.mozilla.org/pub/thunderbird/releases/102.15.1/

2. Uninstall 115.

3. Delete "compatibility.ini"-Files for all Profiles.

4. Go offline to prevent auto-update of 102.

5. Start 102 from console with " -P --allow-downgrade" - option and select the profile you want to use if there is more than one (for me it was "default"). Had to start it like that every time from then on, though, because without it it doesn't find the profile. Slight drawback I gladly accept!

6. Disable Auto-Update: I used the "Config Editor" [Button in Settings->General] for this:

 - set "app.update.auto" to false

But to be honest I am unsure if that last one will be good enough to really deactivate the auto-update. For now it seems to be working for me.

Be aware though that 102 is an old version with security issues...

A much bigger drawback that truly worries me, but at least my eyes aren't hurt by that awful new GUI anymore. And I can scroll down all the way to the bottom of a Folder again, something 115 prevented for whatever reason.

To Mr. Garrison You being a web developer should know that System Restore does not restore the whole computer. It restores the system programs and files and user programs. It does not restore data. All your data stays intact.

You are correct. But you can't "pick and choose" only what you want. That's the problem. It restores, won't hurt your data, but it does make changes that I don't want to other programs. I'm not only considering the data of TB. Other programs are at risk, and even though it "should not" harm anything, it's just not worth taking the chance. Hence my opting to only install and revert the version of TB. I saved the TB profile to an external drive before restoring TB.

The fact that TB refused to restore without my downloading a previous version was the first sign that I had no intentions of disturbing the entire computer.

TB failed to launch after installing Supernova. I had no desire to "knowingly" make changes to anything else. TB is a critical part of my business. Without E-mail that's simple to use, it makes life miserable. My only other option was to use Webmail - uhg! These people who keep saying, "Just work through the issues...." What?! How do you "work through" the E-mail software refusing to launch?!

I prefer to "fix" the part that is broken and not take any chance that other parts are going to be disturbed in the process of a system restore. I've used system restore many times in the past. In this situation, it seemed much more logical (for me) to simply address TB. As it was, Supernova refused to allow me to restore to a previous version. Running the command through "run" did nothing until I installed 99.0b.2 and ran the command. Supernova won't launch on my machine, and won't let me restore to a previous version. How do you "work through" that? So I just did what seemed the best option - for me. Perhaps that's not as easy for others. It was for me.

jherbjr, The last restore point says: 10/6/2023 Installed Mozilla Thunderbird 102.9.1 x64 en-US I guess that was from when I ran the msi file yesterday. I found it in Control Panel, Uninstall. Right below that I found Mozilla Thunderbird (x86en-US installed 9/30/23 Version 115.3.1 Below that I have Mozilla Thunderbird 78.0 (x86 en-US) installed 1/7/23 Version 78.0.

I searched for "Thunderbird" and found one in the folder where I originally installed TB many years ago...not the default folder. It is 115. So the upgrade to 115 installed over my previous TB

I also found a TB where Mozilla wants to install it. It is version 102.9.1 but when I start it it is like a cold start. It wants me to fill in the first account. It knows nothing about the 20 or so accounts I have.

I am not sure how to untangle this.

I have used it several times and never a problem.

It should be showing more than one restore point. There is a button to click to have it show all points.

I clicked the button. That is all.

My Request https://support.mozilla.org/en-US/questions/1426708

No guarantees, Exit Thunderbird if running.

Try:

    computer search type: 'Run'
    select the 'Run' app
    Enter: thunderbird.exe -P --allow-downgrade
    click on 'OK'  

Please remember that the overall design of 115 will not revert to the view of 102. My encouragement is to stay with 115 and work through the transition.

Thanks for your suggestion. I tried it: no joy.

What worked for me:

Download Thunderbird 102.15 installer or Portable Version.

https://download.mozilla.org/?product=thunderbird-102.15.1-SSL&os=win64&lang=en-US

WITH THUNDERBIRD CLOSED:

1 Open Thunderbird Profile folder. 2 Delete compatibility.ini file from the Profile folder you opened. 3 Install the Thunderbird 102.15 installer you downloaded. 4 Relaunch Thunderbird.

Version 102 should be re-installed.

Additional details -

I dual-boot either Linux (Debian Bullseye) or an old version of Windows. The Thunderbird version Debian supports is v102.13.1 which won't / can't support a v115 profile, hence, my requirement to continue using v102.15.1 in the Windows instance.

Did you uninstall 115 first?

Did you uninstall 115 first?

Excellent question; no.

Deleting the compatibility.ini file from my Profile folder allowed the 102.15 installer to overwrite the 115 installation.

I did a system restore. It reloaded all the system and user programs. Uninstall is moot.

I followed the steps posted by redbike9 above, including hiding the compatibility.ini (moved to desktop). I ran the install to the suggested folder and got 102.15.1 with launch selected It opened but it has no profiles. I went through these steps https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#w_starting-the-profile-manager And selected the profile C:\Users\Pete\AppData\Roaming\Thunderbird\Profiles\xzi4blv2.default Which is the one that is 16.4 GB. Restarted TB 102.15 and still no profiles. I did some mucking around closing TB102 and starting TB115. Reinstalled 102 a few times and SUCCESS...for now anyway.

Thanks a bunch....

Oh, under settings, General, 4/5 of the way down, "Allow Thunderbird to 'Check......"

posted this bug tonight for v 115 anything-but-superNova. Yet another way it is broken. https://bugzilla.mozilla.org/show_bug.cgi?id=1858351

essentially 115 now ignores the configuration setting (Do Not) Automatically mark message as read.

Since I now have clients who are dropping the ball for all *their* clients because the team can't co-ordinate easily, and can't rely on what the shared IMAP mailbox is showing them (we've been doing this for 20 years!), we have to roll back to a working version.

Kudos to everyone here who has posted the useful information. Tip to the Mozilla dev team - keep the last known-good version handy for at least a little while. Nobody is happy when you screw with their long-established workflow.

thunderbird 115.0 is unacceptable; how can I revert to previous version?

Totally agree. 115 is a DISASTER looks terrible, slow as hell, nothing where it should be and the position of the menu bar, well for heavens sake who decided to put it there instead of where it should be at the very top, where are the spacers etc. for the mail bar, This is the worse version of thunderbird EVER. for god's sake issue a roll back!

just for clarity/completeness, here is what worked for my clients on win10

download the .exe installer -> https://download-installer.cdn.mozilla.net/pub/thunderbird/releases/102.15.1/win64/yourLang/*.exe

find and back up your current Profile, AND turn off automatic updates:

- run thunderbird
- find your "help" menu (it moves around by version)
- look for "Troubleshooting Information" (or similar - this also varies by version) and open that
  - look for Profile Folder, and there should be a button "open folder"
    - click on the button ("open folder") and capture the path from whatever file manager you are using
    - e.g. C:\Users\peter\mozilla\email
- *copy* that directory to another location as a backup, and rename it something like "borked_tbird_profile_v115_bug"
- or, alternately use an archiver (7-zip, RAR, etc.) to make an archive of that directory with a similar name to the above.

- open settings (app, not account)
  - General -> Updates 
    - select "Check for updates, but let me choose whether to install them"
    - if you see "Use a background service to install updates” below this option, then uncheck/unselect it, as well.

close thunderbird

un-install tbird from the machine

launch the just-downloaded "Thunderbird Setup 102.15.1.exe" application, and install tbird. - *uncheck* the "Launch Mozilla Thunderbird now" option - that is *DO NOT* run Tbird from the installation process!

 - if you do run it, choose EXIT at the next prompt.

launch the Run Command (WinKey + r) - enter thunderbird -P --allow-downgrade - (can also do this from a cmd window) cross your fingers for luck, and click on button "start thunderbird"

click on "help" menu -> About Thunderbird -> S/B showing 102.15.1

resume normal operations

in ubuntu, I used jondark's process, but he neglected to mention executing 'which thunderbird' before removing it (in order to know where to put it). I should note that I have removed all of snap from my ubuntu, so this may not be very useful to you, but in my snapless unbuntu, the downloaded tar.bzip2 file is extracted (as root) to /usr/lib/thunderbird, and then a symlink is created in /usr/bin to the thunderbird binary, thus (as root) 'ln -s /usr/lib/thunderbird/thunderbird /usr/bin/thunderbird'

for the record, I uninstalled thunderbird v115 this way (as root) dpkg -l | grep thunderbird dpkg --purge thunderbird thunderbird-locale-en thunderbird-locale-en-us

I have been using Thunderbird for at least 15 years, on both Mac and Linux, and have never been as dismayed at an upgrade as I am with 115. I generally install all updates when prompted by Ubuntu (using Ubuntu Linux 22.04 LTS for past 12 months; have used Ubuntu off and on since 2006), so I wasn't consciously seeking to upgrade Thunderbird, with which I had no complaints. Some specifics:

1. I was previously unaware of the concept of "Density," so I don't know whether this is new or not. After upgrade, I became immediately aware that folder layouts were more vertically squeezed (tighter leading, in old typographic terms). I eventually discovered that the upgrade had moved me to "Compact" density rather than "Default." Problem: "Compact" density meant that when, starting from the folder pane on the left, I clicked within the pane for a given folder, the display for the folder did not move to the bottom of the pane as it always did previously. Rather, it moved to near the bottom of the folder, meaning that I had to scroll down to reach the bottom of the folder where the newest messages are found. Switching to "default" density appears to have corrected this.

2. When I click on any individual message, the point size of the body of the message is very small: approximately 4 or 5 point in traditional typographic terms. That means I have to hit "Ctrl-Shift=+" multiple times to get the message up to a legible size. This increase in body copy point size does not survive a quit-and-restart of Thunderbird.

Does anyone else have this problem... After the "upgrade" to Supernova, on my calendar page any tiny movement of the mouse wheel sends the calendar scrolling by months or even years. This is a new phenomenon only after the upgrade. I've tried every suggested remedy I could find on the internet --to no avail. I have Windows 11 and Logitech M325 mouse.

ALERT ALERT ALERT. A new 115 came out last night (for me). I saw the notice and stupidly allowed it. Then I had to go through the procedure to return to 102.