Windows 7 .NET program closes at startup: "Unhandled exception"

Hi Peter,
So you're a developer huh? Not familiar with GitHub thing at all; first time I've seen it. It looks like a GNU public-domain type suite of programs though. Have you tried their Support page here: GitHub Help

Not sure what other programs are being affected; but generally speaking, running multiple versions of .NET FRAMEWORK, especially ones as old as .NET v2X is not good when running side-by-side with newer versions of .NET such as V4x and v5x. Programs running .NET v2x are REALLY OLD, such as running back on W2k or XP. We are talking about OS databases from 17 years ago and 15 years ago respectively. Those tend to be legacy apps that are often out of date or even obsolete. With W7 you might be able to run those apps in the XP-MODE and see if you get the same results. Chances are, you are getting inconsistency-chain errors when library calls are being made to both old .NET v2x modules and .NET v4x modules.

You have a few things you might try:
1.) Have you installed any of these programs on another Windows computer with W7 or newer version? Do you get the same result? If not, you should try this. If you get the same result or another error code, you should check that computer and remove the any .NET newer than v2x on that computer **you probably want to set a Restore Point on that computer you are testing with, or better yet create a Backup Image File using free Macrium, Acronis, or EASE Todo backup software first!**
2.) Using that same 2nd computer for app testing, try running one of your other programs that uses the newer .NET v4x platforms. Do you get the same result? If you do, you need to check for and remove ALL OTHER VERSIONS OF .NET such as .NET v3x or .NET v5x etc. and then retest. Newer programs or databases should run on W7/W8x/W10 correctly, otherwise there could be conflicts as mentioned above. If that newer program fails to run on the 2nd test computer with only .NET v4x installed; there probably is a problem with the code and you can't fix it unless you have access to the source code and appropriate compiler tools set. Otherwise, you have to get a hold of the original programmer and try to get him to fix or patch that program!That could be difficult.
3.) .NET Framework issues are notoriously difficult to fix; the key here is to test 1 program on 1 computer, using only one (1) version of .NET Framework installed at a time. If you can't do this, you'll have to purchase another hard drive for the computer you have now and load up W7 from scratch with no other apps installed other than basic web updates (adobe & java), and the required .NET version needed for your program; i.e.: the TailWin app. If it magically begins working, you have a conflict with other newer apps that are being loaded by W7 startup. You can use MSCONFIG.EXE in the Run command box to remove one app at a time from your Startup list of apps, reboot, and by removing all of them, you can put back 1 app at a time *using Selective Startup Option*, and wait for your app to fail; this requires a reboot after each app is put back so it is quite time consuming. This will tell you the app or apps that are crashing your app, the TailWin app in this case. If you NEVER get the app (TailWin) to work on a clean W7 OS loaded HDD, then there is probably something wrong with the copy you downloaded, or possibly the version of the app you downloaded could be corrupted--try re-downloading and running again. This should fix it.
Of course, there is the possibility that the app was never coded correctly, and no one on the planet has ever had it working correctly! Or, the author of the app, never patched it to run on W7 (remember any app coded for .NET v2x is using out of date code and libraries).
4.) E-mail the GitHub folks and tell them about your problem; and ask them SPECIFICALLY if that program was ever tested on W7? Yes or No? If the answer is No and the program author never tested it on W7, then it never worked, and it will never work on any W7 computer!! If the answer is Yes, then ask for help from the author or their support forum.

By the way, if you think troubleshooting .NET problems is tough on desktop clients; wait until you try fixing it on a network server!! Uggghhh!

Let us know how it goes. Possibly one of our expert programmers may have some other suggestions for you too.
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