There is a particular set method to being able to go back to the last 68 version after updating to a 78 version.

Need to set updates to ask, change the address book, uninstall, then download old and reinstall, but do not auto start. Then use command line to force a backwards compatibily allowance.

In the 78 version:

• Menu app icon > Options > General
• Scroll down to 'Updates' section
• select 'check for updates, but let me choose whether to install them'

To add also those email addresses back follow below steps: In Thunderbird

• Help >Troubleshooting Information.

Under Application Basics section about 8 down in list see 'Profile Folder'.

• Click on 'Open Folder'

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

• Exit Thunderbird

In the profile name folder - you will find the old address book files with extension .mab.bak - those files (abook and history) you need to:

• -rename them to .mab (so remove the .bak part) eg: 'abook.mab.bak' becomes 'abook.mab'
• -rename abook.sqlite and history.sqlite by adding .bak to the name. eg: abook.sqlite.bak
• Do same for any other address books you created.

Now uninstall Thunderbird program. You could just delete the Mozilla Thunderbird folder from here:

• C:\ Program Files (x86)\Mozilla Thunderbird
• then empty the computer 'Recycle Bin'

Then get download from here:

• http://ftp.mozilla.org/pub/thunderbird/releases/68.12.1/
• choose appropriate OS, then choose language, then download the Thunderbird Setup 68.12.1.exe file

Run the downloaded .exe file to install. On the last step of the installation do NOT select to start TB because you will need to run a command to allow you to downgrade.

Windows OS:

• In search type : Run
• Select the 'Run' app
• Type: thunderbird.exe -P --allow-downgrade

note there is a space before and after -P

• click on OK

Profile Manager starts select the desired profile name click on 'Start Thunderbird'.

Thank you for the detailed script. I use two computers. the primary, C1, has the problem TB. The backup, C2, which i'm using right now, uses TB V68.12.1 flawlessly. I copied the profile it uses to Flash and then to the Profiles Folder in C1. At your penultimate "select profile" step I deleted other profiles and selected the trusted profile. First tried the "8 char string.default" then tried just "default." In each case got message "... profile can't be loaded..." Since I can't get to TB I can't check the path. Outside TB the path to the desired profile seems OK to me. Please continue with your excellent help.

You seem to have deviated from the instructions. The instructions were designed to allow a downgrade on the original - now deleted profile - which had been upgraded to work on 78.4.1. At no point did I say copy over and use a version that had only worked on TB V68.12.1. Nor did I advise you to delete any profiles.

If you had completely removed/uninstalled version version 78* and then installed version 68.12.1. but did not start thunderbird. Then copied over a profile that had only worked on 68.12.1, you would not need to use the allow downgrade because you were not downgrading. You merely needed start the Thunderbird Profile manager  : In search type : Run Select the 'Run' app Type: thunderbird.exe -P and select the copied over profile click on 'Start Thunderbird'

At this point, it is possible the 'profiles.ini' has no idea what you want to do.

• Exit Thunderbird.
• Start The Profile Manager:

1. In search type : Run
2. Select the 'Run' app
3. Type: thunderbird.exe -P

• Click on 'Create Profile'
• call it 'Default User'
• Then select 'Choose folder'
• select the correct profile name folder - the one you copied over.
• click on 'select folder' button
• click on 'Finish'

Select 'Default User' profile and clickon 'Start Thunderbird'.

Your latest script WORKED! Thank you for Your help and patience. What right do I have to think, right? From Casablanca. i guess I don't understand the intricacies of the Profiles Folder. Since you're very helpful, more questions. 1. How avoid outgoing email auto double spaced? 2. Are Options and Account Settings duplicates of one another or what? 3. Is there any compelling reason for me to "update" to V78? 4. I contribute to Mozilla every year thinking I was supporting both Firefox and TB. TB support is on the Mozilla site. How do I contribute to TB?

I notice that you incorrectly marked your comment as the 'Chosen Solution' and not my comment containing the actual 'Chosen solution' which makes it very confusing for anyone searching the forum for a solution to their issue if they have same question as yours.

Usually each question created only contains information specific to that question. If you have a completely different question then it should be a new question. However, on this one occassion I'll provide some basic info, but if you need more help you should create a new quesion.

1. How avoid outgoing email auto double spaced? Menu app icon > Options > Options > Composition > General uncheck: 'Use Paragraph format instead of Body Text by default'

2. Are Options and Account Settings duplicates of one another or what? No they are very different. Account Settings is very specific and relates only to the Account itself such as the 'Server Settings' used to connect to a server and selecting the specific Folder to store 'Sent' messages etc. Whether an account uses HTML or not by default to compose messages. Usually, once these settings are created, you do not need to access it unless something needs to change.

Options is more generic and default setting to all other aspects of Thunderbird. Such as Composition defaults. Alerts regarding new mail. Tags and what default programs are used to open specific attachments and much more.

3. Is there any compelling reason for me to "update" to V78? Some people choose not to update because they have become accustomed to using certain add-ons that are not available for version 78. Personally, I always read the 'Release notes' that are offered when each version is released before I update to help me choose when and if I should update. I do update with each release mainly because various security and bug fixes. I also need to run more than one installation to cover various versions so I can help other users in the Support Forum. As a heads up, it is always a good idea to create a backup of the 'Roaming'/'Thunderbird' folder prior to performing an update. My update settings (located in Options) say to check for updates but let me choose when to update, this affords me time to create a backup first.

4. I contribute to Mozilla every year thinking I was supporting both Firefox and TB. TB support is on the Mozilla site. How do I contribute to TB? This is the link: https://give.thunderbird.net/en-US/?utm_source=start_page_tb_release&utm_medium=referral&utm_content=paragraph_text

You can also locate this via Thunderbird - 'Help' > 'Make a donation'

Thank you for your help, patience, and understanding. Although I'm computer hardware and software literate, it's probably been at least two years since I've had to get detailed help with TB. I have a STEM background but for 26 years most of my time has been consumed in managing a seven figure stock portfolio. I sincerely appreciate everything you and your colleagues do to support users of TB. I will support both Mozilla and TB with cash.

Vumbo, you are more forgiving than I: I wouldn't contribute washers never mind coin to the developers who released v78 on their unsuspecting users and completely screwed up the calendar which I used heavily. I have eventually thrown in the towel, updated to v78.4.3, imported Google calendar with which I had Lightning linked, and called it a day. At least I now have similar functionality. I might consider contributing when the developers remember that the users are the most important consideration, not some mug's notion of "progress". I was appreciative of Toad-Hall's script which did indeed work well, but still left me with a calendar that I could not sync.

The contribution is not just to a developer, it will also support this forum so people can get help and it will also contribute to the survival of Thunderbird. It is a really good email client and it allows you to do all kinds of stuff to alter things. Surely my voluntary contribution is worth something :)

I guess you're right. However, I'm still hopping mad that the versatility and usefulness of such a good application as Thunderbird was so severely compromised by prematurely releasing such a major update before such problems were overcome. (Initially, I lost my local folders as well which would have annoyed me even more if I had not got backups of the important mails in different formats, since even profile backups were useless - I assume because the file type had changed) The point still needs making that updates that break aspects of an app's functionality will alienate as many users as benefited from that aspect - for instance syncing with Google Calendar, which even Microsoft had to introduce to Windows Calendar, or the ability to set email notifications, neither of which are now available in Thunderbird Calendar. However, I am still using Thunderbird which proves your point! (Oh, and I will contribute)

re : for instance syncing with Google Calendar

I have seen reports that this stopped working, but a reinstall got it up and running again. Suggest you try reinstalling 'Provider for google calendar' addon. https://addons.thunderbird.net/en-GB/thunderbird/addon/provider-for-google-calendar/

Thank you for that; calendar data does now survive shutdown. However, having discovered that Google Calendar in Thunderbird allows for email reminders which I have always used & which (inexplicably) Thunderbird Calendar now does not, it is Google's Calendar that I will be using. Best wishes, Richard

Great write-up Toad-Hall. Worked perfectly, thanks.

In my case, it was a voluntary update, but I missed the v68 theme. I find V78 a bit too flat and lacking contrast for separation of elements.

Glad I found Vumbo's thread, because I didn't realize there were additional steps required. I would have assumed otherwise that it was similar enough to v68, and just gone forward with an uninstall and reinstall.