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Windows Apps & Features shows an app installed just before the first signs of trouble: "Microsoft Corporation, Mail and Calendar, 8.15MB, 5/20/2022" July 11, Disabled all App Permissions and Terminated app.

Another unusual symptom is that sometimes email will arrive as normal, but if I leave it in the inbox and try to read it again later it has been corrupted, with the message body replaced with another email. The original email is lost.

July 11, deleted popstate.dat for primary account.

July 13, Avast "secured" three new threats and moved them into Quarantine:

      - Win32:Parite [Inf], c:\windows\syswow64\WiFiService.exe, Process: PID 1864
      - Win32:Parite [Inf], c:\windows\syswow64\WiFiService.exe, Process: c:\Program Files (x86)\MySQL\bin\mysqld-nt.exe
      - Win32:Malware-gen, c:\windows\syswow64\lpjro.dll,  Process: c:\Program Files (x86)\MySQL\bin\mysqld-nt.exe

Thank you for any help and advice you are willing to share.

July 15th, An observation.... It seems that if I move Inbox emails to subfolders as they arrive, new emails are not getting corrupted on arrival. Will continue to test this further. Still getting daily popups "TB can't update..." Any suggestions greatly appreciated.

re:Still getting daily popups "TB can't update..."

The update history tells you the last properly logged update. It does not mean that is the version you are actually using. You are probably getting that error because the history has not recorded the last update.

You can find out what version is being used in either of the following locations:

• Menu icon > Help > About Thunderbird

OR

• Menu icon > Help > More Troubleshooting Information
• Under 'Application Basics'
• Second line 'Version'

See if clearing all the old cache helps.

• Exit Thunderbird.

Access this location.

• C:/Users/User Account/Appdata/Local/Thunderbird/Profiles/

In the 'Profiles' folder - Delete the 'profile name' folder.

Please note you must be in the Appdata 'Local' folder - not the 'Roaming' folder as that contains your profile and emails. You do not want to delete anything in the 'Roaming' folder.

You can get to the Appdata folder by doing the following:

• In bottom search type : %Appdata% and select the 'Appdata' app option
• Then you can click on 'Local', then 'Then 'Thunderbird' and finally 'Profiles'

See image below as guide.

Then restart Thunderbird.

Hi Toad-Hall, Thank you very much for your reply and suggestions. I have read many of your previous posts while troubleshooting this issue and appreciate your time & expert advice.

Troubleshooting Information says I'm running 102.0.1. About Thunderbird says "Thunderbird is up to date". I just checked the TB site and see that 102.0.2 is now released (so it is not up to date).

On your advice, I deleted the old cache and restarted TB.

Then I downloaded and installed TB 102.0.2, but the three problems still remain.

Corrupted messages.

Update history still says "No updates installed yet." Received same popup "TB can't update..."

Advanced Account Settings is still greyed out, still not checking primary account when I click "Get Messages".

I emailed 20 test messages to various accounts. The first 15 arrived properly, but by the time all 20 arrived, messages 8 & 9 were both corrupted. This fits with my observation that if I keep the inbox cleared as emails arrive (by moving messages to subfolders), the messages are not corrupted. I have a variety of subfolders in the Inbox, but none of the messages in these are corrupted.

Thanks again for helping to sort out this weird problem. Any other suggestions are eagerly welcome! :) Thank you very much!

AVAST could be part of the problem. The 'Update history' is not being able to get set and is triggering the update, but it cannot and anyway you are up to date. I believe AVAST is causing the block. It has been known to do this.

Exit Thunderbird. Access Firewall which might be controlled by AVAST and set Thunderbird and the Thunderbird Software Updater program as allowed programs.

Then add an exception in AVAST anti-virus. Info at link below: Although it is generally not recommended, you may want to exclude certain files, folders, or websites from being scanned by Avast Antivirus. Add an exception Setting a global exception will exclude individual files, folders, or websites from all scans and shields.

Add as exception: 'aus.thunderbird.net' and also 'www.thunderbird.net' use info at link:

• https://support.avast.com/en-ww/article/Antivirus-scan-exclusions

I would also advise you set the Thunderbird profile folder as an exception so not to scan it.

Whilst this might not be an immediate fix on the machine running current version as you'll have to wait for update. When the next update comes through see if this gets added to the history.

Hi Toad-Hall, Thank you for these suggestions. A few weeks ago, I disabled the Avast Mail Shield, and added these three exclusions. But to follow up on your suspicion, I removed Avast Free Antivirus with avastclear.exe, uninstalled TB, and installed TB 102.0.2. Next I planned to reinstall Avast Free Antivirus, but instead found a similar product called Avast One Essential, so I installed it instead. So far out of about 60 messages, none are corrupted, and the "TB can't update" popup has not returned. Problem solved! Thank you very much for your assistance!