i get no error message. all i get is what is written in hellfire.err and i included that in my post. the normal diablo does start without issues. only hellfire does not start.

Please show us the window(s) which tell you this.

Sorry sir didn't know you took an exam in computers. Did they have an exam in hellfire? Because you clearly skipped this one : - D

You've been offered help in the form of devilutionx, which works flawlessly.
Even gog support answered you.
But yeah surely everyone is wrong and you are right. Keep being delusional. Have problems with hellfire? Guess what, nobody cares. You've been rude towards people that have been trying to help you, you are on your own. And you don't sound like someone that knows anything about computers.

The Hellfire dump doesn't blame any particular module. This can, but does not necessarily, indicate a problem with DEP conflicting with dynamic code generation.

I haven't insulted you yet, though you have presented a very tempting target. I asked for confirmation that it was disabled because it is the most reasonable explanation, and I wanted to verify that your attempt to turn it off had done what you thought you did. Since you are so confident that you have disabled DEP for Hellfire, I will assume that you have done so. I have no other ideas, and therefore cannot help you further.

if you do not have a solution, i accept that. i even tried inserting the diablo disc, in case that would help. i tried everything i could think of. i have no issues with running it in windows 7 or windows 10, it is just in windows 8.1 where it fails to start.

Try to rename _ddraw.dll and start directly from hellfire.exe. For testing if there is something between Win8.1 x64 and GOG's wrapper used by launcher, diablo dx and by hellfire.

that did not help. i have always started directly from hellfire.exe by the way. hellfire never used the original executables in the first place. i have the disc version and that installs hellfire specific data and its own executable. it does not even require diablo.exe to run, just the disc. i already installed the disc version and both version have the same issue: black screen before it goes straight back to desktop.

i figured it out eventually. the problem was several data files, that was not compatible with windows 8.1. those are: storm.dll, smackw32.dll(videoes does not work because of that),_ddraw.dll and standard.snp. compatible versions of all of those files exist in the dx folder. copying them from the dx folder to the hellfire folder enables hellfire to run.

DLL (Dynamic Link Library) files are not data files. DLL files are executable files that contain code and resources that can be used by multiple programs at the same time. They are often used to provide common functionality that can be shared among different programs, such as graphics rendering or sound processing. In contrast, data files contain specific information that is used by a single program or application.