This is more likely an issue with computer and VC++ and not Thunderbird. Use the command line sxstrace.exe tool and it may point to what is failing.

Try to repair a side-by-side error using the Repair tool in the "Programs and Features" section of your Windows Control Panel. If that doesn't fix the problem, you can manually reinstall all your Microsoft Visual C++ packages.

These links may provide you with some useful info.

• https://www.codeproject.com/Articles/43681/Side-by-Side-Configuration-Incorrect

• https://answers.microsoft.com/en-us/windows/forum/windows_7-pictures/error-the-application-has-failed-to-start-because/df019c0d-746e-42d0-ad68-465e18e3f3ef

• https://www.vistax64.com/threads/side-by-side-configuration-is-incorrect.245768/

But you may also need:

• https://support.microsoft.com/en-in/help/2977003/the-latest-supported-visual-c-downloads

I doubt that reinstalling Thunderbird will help. You need to get all the VC++ sorted. You may need to remove and reinstall several versions of V C++. As described in those links.

Please note that uninstalling and reinstalling Thunderbird, only uninstalls and reinstalls the program - please make sure you reinstall the same version as you uninstall. As you have a current installation and therefore mail accounts etc, you should create a backup because emails are important documents and I would always advise a backup of anything you consider important.

BACKUP:

If you have allowed the profiles to be created in the default location then you will find them here:

• C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\

Note: the 'Appdata' folder is a hidden folder, so you may need to make hidden files and folders visable.

• Exit Thunderbird (If running !)
• Copy the 'Thunderbird' folder as indicated in bold above and save on an external device. It will save all profiles, mail accounts, emails (assuming you have fully downloaded copies), address books, preferences, etc etc.

Well thankyou very much.I did install some VC++ versions without uninstalling first because i was in a rush,so maybe if i had uninstalled them first it would be fixed now. I,m going to try uninstalling all of them 1 by 1,then reinstall them 1 by 1. This all started because i was using Avast free version,and during a scan it found a false positive in thunderbird,but the screen went away for some reason before i could react.I removed Avast after,but it was too late.I was only using it because i was under the wrong impression that micorsoft security essentials support was over,but it is not.

just reinstall Thunderbird.... my guess is avast has deleted something important and the re install will replace it. As mail is stored separately from the program you loose nothing in reinstalling it.

I suggest you get a fresh installer from https://www.thunderbird.net just to be sure you have the latest version.

Thanks.Just 1 question here...should i uninstall thunder first before reinstalling it,or just install it without uninstalling it first?

Thanks.Just 1 question here...should i uninstall thunder first before reinstalling it,or just install it without uninstalling it first?

Whatever you feel like. It should make no difference to Thunderbird.

Thanks. I backed up my profile,but it didnt matter because downloading my current version of thunderbird,and just installing it did the trick. Thanks much all. I also after uninstalling the VC ++ redists ,found a much quicker way to install all of them here... https://www.techpowerup.com/download/visual-c-redistributable-runtime-package-all-in-one/