1. Do Settings > General > type "config" into the search 2. open Config Editor 3. Search for "app.update.log" and set it to "true". 4. Restart Thunderbird. 5. Do Help > About 6. Open Tools > Developer Tools > Error Console 7. Type AUS into the filter 8. Please copy/paste everything starting with "AUS:"

Thank you for reply. The log follows. Almost looks like there are two problems. One with some security not allowing TB to write in the folder and another not getting response when asking for update.

AUS:SVC UpdateManager:_loadXMLFileIntoArray - XML file does not exist. path: C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\8216C80C92C4E828\active-update.xml Successfully loaded OpenPGP library rnp.dll version 0.16+git20220124.f06439f7.MZLA from C:\Program Files (x86)\Mozilla Thunderbird\rnp.dll RNPLib.jsm:100:15 UTM:SVC TimerManager:registerTimer - timerID: region-update-timer interval: 604800 skipFirst: false Trying to load C:\Program Files (x86)\Mozilla Thunderbird\libotr.dll OTRLib.jsm:64:11 Successfully loaded OTR library C:\Program Files (x86)\Mozilla Thunderbird\libotr.dll OTRLib.jsm:72:13 Found 0 public keys and 0 secret keys (0 protected, 0 unprotected) RNPLib.jsm:301:15 services.settings: Failed to load last_modified.json: TypeError: NetworkError when attempting to fetch resource. Utils.jsm:330

Component returned failure code: 0x80550013 [nsIMsgPluggableStore.createFolder] Pop3IncomingServer.jsm:135

tb.account.size_on_disk - Attempted to set the scalar to an incompatible value. 4 tb.account.size_on_disk - Truncating float/double number. 4 about:accountsettings : Unable to run script because scripts are blocked internally. 30 AUS:SVC Creating UpdateService AUS:SVC Logging current UpdateService status: AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC getCanApplyUpdates - testing write access C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\8216C80C92C4E828\update.test AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC getCanApplyUpdates - able to apply updates AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC gCanStageUpdatesSession - testing write access C:\Program Files (x86)\Mozilla Thunderbird\update.test AUS:SVC gCanStageUpdatesSession - unable to stage updates. Exception: [Exception... "Component returned failure code: 0x80520015 (NS_ERROR_FILE_ACCESS_DENIED) [nsIFile.create]" nsresult: "0x80520015 (NS_ERROR_FILE_ACCESS_DENIED)" location: "JS frame :: resource://gre/modules/UpdateService.jsm :: testWriteAccess :: line 519" data: no] AUS:SVC Elevation required: false AUS:SVC Other instance of the application currently running: false AUS:SVC Downloading: false AUS:SVC End of UpdateService status AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC Checker: checkForUpdates, force: true AUS:SVC Creating UpdateService AUS:SVC Logging current UpdateService status: AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC getCanApplyUpdates - testing write access C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\8216C80C92C4E828\update.test AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC getCanApplyUpdates - able to apply updates AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC Elevation required: false AUS:SVC Other instance of the application currently running: false AUS:SVC Downloading: false AUS:SVC End of UpdateService status AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC waitForOtherInstances - beginning polling AUS:SVC waitForOtherInstances - no other instances found, exiting AUS:SVC Checker:getUpdateURL - update URL: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 AUS:SVC Checker:checkForUpdates - sending request to: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 NS_ERROR_ABORT: Certificate issuer is not built-in. CertUtils.jsm:183 AUS:SVC Checker:onLoad - request completed downloading document AUS:SVC Checker:onLoad - Getting sslStatus failed. AUS:SVC Checker:onLoad - there was a problem checking for updates. Exception: TypeError: this._request.responseXML is null AUS:SVC Checker:onLoad - request.status: 302 AUS:SVC getStatusTextFromCode - transfer error: Aktualizační XML soubor nebyl nalezen (404), default code: 404 AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC Checker: checkForUpdates, force: true AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC Checker:getUpdateURL - update URL: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 AUS:SVC Checker:checkForUpdates - sending request to: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 NS_ERROR_ABORT: Certificate issuer is not built-in. CertUtils.jsm:183 AUS:SVC Checker:onLoad - request completed downloading document AUS:SVC Checker:onLoad - Getting sslStatus failed. AUS:SVC Checker:onLoad - there was a problem checking for updates. Exception: TypeError: this._request.responseXML is null AUS:SVC Checker:onLoad - request.status: 302 AUS:SVC getStatusTextFromCode - transfer error: Aktualizační XML soubor nebyl nalezen (404), default code: 404 AUS:SVC UpdateService:removeDownloadListener - Warning: Didn't remove non-existent listener

Here is the log after I run TB as admin:

AUS:SVC UpdateManager:_loadXMLFileIntoArray - XML file does not exist. path: C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\8216C80C92C4E828\active-update.xml Successfully loaded OpenPGP library rnp.dll version 0.16+git20220124.f06439f7.MZLA from C:\Program Files (x86)\Mozilla Thunderbird\rnp.dll RNPLib.jsm:100:15 Trying to load C:\Program Files (x86)\Mozilla Thunderbird\libotr.dll OTRLib.jsm:64:11 Successfully loaded OTR library C:\Program Files (x86)\Mozilla Thunderbird\libotr.dll OTRLib.jsm:72:13 Found 0 public keys and 0 secret keys (0 protected, 0 unprotected) RNPLib.jsm:301:15 UTM:SVC TimerManager:registerTimer - timerID: region-update-timer interval: 604800 skipFirst: false services.settings: Failed to load last_modified.json: TypeError: NetworkError when attempting to fetch resource. Utils.jsm:330

Component returned failure code: 0x80550013 [nsIMsgPluggableStore.createFolder] Pop3IncomingServer.jsm:135

tb.account.size_on_disk - Attempted to set the scalar to an incompatible value. 4 tb.account.size_on_disk - Truncating float/double number. 4 about:accountsettings : Unable to run script because scripts are blocked internally. 30 AUS:SVC Creating UpdateService AUS:SVC Logging current UpdateService status: AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC getCanApplyUpdates - testing write access C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\8216C80C92C4E828\update.test AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC getCanApplyUpdates - testing write access C:\Program Files (x86)\Mozilla Thunderbird\update.test AUS:SVC getCanApplyUpdates - able to apply updates AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC gCanStageUpdatesSession - testing write access C:\Program Files (x86)\Mozilla Thunderbird\update.test AUS:SVC gCanStageUpdatesSession - testing write access C:\Program Files (x86)\update.test AUS:SVC gCanStageUpdatesSession - able to stage updates AUS:SVC Elevation required: false AUS:SVC Other instance of the application currently running: false AUS:SVC Downloading: false AUS:SVC End of UpdateService status AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC Checker: checkForUpdates, force: true AUS:SVC Creating UpdateService AUS:SVC Logging current UpdateService status: AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC getCanApplyUpdates - testing write access C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\8216C80C92C4E828\update.test AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC getCanApplyUpdates - testing write access C:\Program Files (x86)\Mozilla Thunderbird\update.test AUS:SVC getCanApplyUpdates - able to apply updates AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC Elevation required: false AUS:SVC Other instance of the application currently running: false AUS:SVC Downloading: false AUS:SVC End of UpdateService status AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC waitForOtherInstances - beginning polling AUS:SVC waitForOtherInstances - no other instances found, exiting Relativní umisťování řádků tabulky a skupin řádku je nyní podporováno. Tato stránka může vyžadovat aktualizaci, protože může být závislá na této funkci. preferences.js:268:2 AUS:SVC Checker:getUpdateURL - update URL: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 AUS:SVC Checker:checkForUpdates - sending request to: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 NS_ERROR_ABORT: Certificate issuer is not built-in. CertUtils.jsm:183 AUS:SVC Checker:onLoad - request completed downloading document AUS:SVC Checker:onLoad - Getting sslStatus failed. AUS:SVC Checker:onLoad - there was a problem checking for updates. Exception: TypeError: this._request.responseXML is null AUS:SVC Checker:onLoad - request.status: 302 AUS:SVC getStatusTextFromCode - transfer error: Aktualizační XML soubor nebyl nalezen (404), default code: 404 AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC isServiceInstalled - returning true AUS:SVC shouldUseService - returning false AUS:SVC Checker: checkForUpdates, force: true AUS:SVC UpdateService.canUsuallyCheckForUpdates - able to check for updates AUS:SVC UpdateService.canCheckForUpdates - able to check for updates AUS:SVC Checker:getUpdateURL - update URL: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 AUS:SVC Checker:checkForUpdates - sending request to: https://aus.thunderbird.net/update/6/Thunderbird/102.0/20220627231524/WINNT_x86_64-msvc-x64/cs/release/Windows_NT%2010.0.0.0.19044.1826%20(x64)/ISET:SSE4_2,MEM:16315/default/default/update.xml?force=1 NS_ERROR_ABORT: Certificate issuer is not built-in. CertUtils.jsm:183 AUS:SVC Checker:onLoad - request completed downloading document AUS:SVC Checker:onLoad - Getting sslStatus failed. AUS:SVC Checker:onLoad - there was a problem checking for updates. Exception: TypeError: this._request.responseXML is null AUS:SVC Checker:onLoad - request.status: 302 AUS:SVC getStatusTextFromCode - transfer error: Aktualizační XML soubor nebyl nalezen (404), default code: 404

I fixed the problem. It was bothering me that in the first log TB could not write in the folder. So I stopped all shields in Avast Security and restarted TB and it found the update and installed it automatically.

So the trouble is Avast. Do you know how to set up Avast so that it would allow TB to update? I dont want to make just general exception for TB if possible.

Thank you again for your reply that pointed me in the right direction.

It is possible Avast is blocking a necessary link, can you do the following so it can be tested. Info at link below: 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

Then restart Thunderbird.

Hopefully, Avast will then allow the update to work properly.

It would be useful to know if creating the exception fixes the problem.

Clearly Avast is well aware of it or at least loads of reports on Avast forum https://forum.avast.com/index.php?topic=320195.0 https://forum.avast.com/index.php?topic=319793.0

I also located this : https://support.avast.com/en-gb/article/Use-Antivirus-blocked-allowed-apps/#pc

It is possible Avast is blocking a necessary link, can you do the following so it can be tested. Info at link below: 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

Then restart Thunderbird. Hopefully, Avast will then allow the update to work properly. It would be useful to know if creating the exception fixes the problem. Clearly Avast is well aware of it or at least loads of reports on Avast forum https://forum.avast.com/index.php?topic=320195.0 https://forum.avast.com/index.php?topic=319793.0

That worked! Thank you for your help.