Exited thunderbird Shut down computer to ensure it is fully closed. Start (bootup) computer. Start thunderbird.

Report on results.

No change. The same things happens. I can run Thunderbird in safe mode but I need some addons I use in my daily work. My Thunderbird version is 52.2.0 32bit

Close thunderbird. Check your Firewall, which may be part of an Anti-virus/internet security software package.

Thunderbird should be an 'allowed' program.

If it already set as allowed, set to block, ok it and then access Firewall again and reset to allow. try starting thunderbird.

No change.

I can open Thunderbird in safe mode. I can receive mail and send mail in safe mode. As soon as I try to start Thunderbird normally nothing happens.

What will happen if I move my extensions folder to another folder outside Thunderbird and then start Thunderbird the normal way? If Thunderbird then will start then there's possibly a extension not working correct. Then I can start moving back the extensions one by one to find out which one is the causing the problem.

Are you sure you cannot disable Addons ?

Please check this out. Start Thunderbird in Safe Mode. 'Menu icon' > 'Add-ons' You will see a list of all your addon extensions. By default they are all disabled by Safe mode. However, you should still see 'Disable' and 'Remove' buttons. Click on all of the 'Disable' buttons. Close Thunderbird. Wait for background processes to complete. Start Thunderbird - normal mode.

No, For all my add-ons only Enable or Remove are selectable. No disable button.

What happens if you click on 'Enable' for one of the addons - not 'Lightning' and at the prompt click on 'restart'?

Another thought ... Copy the list of extensions listed at Help > Troubleshooting and post them here.

I have a suggestion after that, but first I want to see the list of addons

First: When I enables one of the add-ons and restarted no change (no start of TB) and when I started TB again in safe mode the add-on was set as enabled but wasn't but I could disable it.

Second: I have added the add-on list from Troubleshooting.

I will try to install the latest version TB again to see what happens.

I have done some testing and now TB works to me. First I downloaded the latest version of TB and installed it. I restarted my PC but there was no changes. I then downloaded and reinstalled Lightning. I restarted TB but the where no changes. I then restarted my PC and started TB in safe mode. I selected to restart TB without add-ons and now TB started without any add-on enabled. I then started to enable one add-on. Started with Lightning. It worked!! I am now enabling one add-on after another. Taking the most important. I have restarted TB every time I have enabled an add-on. So far it works fine. I don't know why this works now but I'm glad it does. Thank you all for your help. I'm glad for your help.