Run Windows in safe mode. Does TB then work?

I actually did a System restore to before installation of Version 128.4.2 (restore failed) but once PC rebooted, it did actually download the missing messages - but minutes later, it went back to the 'Connection was reset' message'

I tried reinstalling the previous version but same thing.

I think what sfhowes is trying to tell you is the issue is most likely not Thunderbird, but the antivirus that has lost it over an unknown version of Thunderbird. Windows safe mode will exclude such things and offer some bread crumbs as to the actual problem software.

Thanks sfhowes and Matt,

I did run Windows in Safe Mode : ..... After restart......

1st response - Connection was refused 2nd response (as before) - Connection reset.

EMail works fine on my phone and on Outlook but not on Thunderbird,

Thanks for your responses

I'm also wondering if there is an issue with Norton Antivirus which I think updated around the same time. I checked applications on Firewall, and Thunderbird is tagged as 'allow...

You mentioned the war; I would guess that Norton appears in dispatches far more frequently than any other antivirus because if is so close to a virus itself. I would almost guarantee the issue is Norton.

My last disastrous encounter with Norton (years in the past now) I was trying to add a new account for a friend. I had to disable something called SONAR, the mail scanner and scanning of encrypted connections before anything started working.

Fundamentally Norton is a huge blocking tool. It was probably 15 years ago the CEO if Symantec came out and said that virus scanning was not going to work and that Norton would be pivoting to allowing known software. The result is Thunderbird updates from say 102.0.1 to 102.0.2 and Norton looses the plot and refused to allow access to the internet. So checking the firewall requires more than a name is required a precise version number for each application is used. Most Nortons users have issues for a day or two until Nortons gets a message from home there is a new version and the problem fixes itself. But the product should no be just blocking stuff waiting for someone from the vendor to approve it. It should be asking you.

Using Outlook, this is not such an issue as they come out with a new version every other year or longer. Market share also means Nortons are more prepared for Outlooks updates.

Check that you have no VPN. For various reasons, they are basically a death knell for email clients. Not the least of which is providers like Google know where your phone is via the email app and you then try and connect from somewhere else, another country often, so the "you have been hacked" stuff kicks in. Very inconvenient and most unnecessary.

Now that Norton is in the same Gen Digital stable as Avast, LifeLock, Avira, AVG, ReputationDefender and CCleaner I would wonder if they are all going to start doing essentially the same thing.

Many thanks for the comprehensive response Matt,

I did disable both Norton AV and VPN but same result on Thunderbird - 'Connection to Server reset'

I am currently reverting to Outlook which is working fine and also considering different Desktop client from Thunderbird (although I had always preferred that in the past).

I take onboard your advices on Norton and may consider another provider (although I have over 6 months subscription left) so I will have to research the best alternative.

Rgds C

I use Norton 360 with no problems. However, Norton runs both Anti-Virus and Firewall. Nortons VPN is a real no no.

So check - Firewall, Anti-Virus scans on profile, switch off Email Protection and check VPN is off

Exit Thunderbird.

In Norton Access Firewall set program as allowed - see image below Also set the thunderbird updater.exe as allowed.

Access Anti-Virus and set exception to not scan Thunderbird profile folders. See image below as guide.

In Norton - this is another option which is ok with me but has solved the connection reset issue with some people - not sure if you have checked this as well.

• Security > Advanced
• Email Protection - switch it off.

check Norton VPN - switch it off if required.

Please note if you have got rid of Norton then Windows default Anti-virus and Firewall will take over so you would need to sort that out as well. The only true way of testing is to restart computer in 'Safe mode with networking', but if you use WIFI then you will need to use an ethernet cable to connect computer to router/hub.