Fixed (in Registry): OpenWith gives a "This app can’t run on your PC"

With a deep dive into the Registry, through searching them on two laptops side-by-side, I was able to extinguish the "This app can’t run on your PC, check with the software publisher (Windows 10/11)" error that was popping up when trying to do an OpenWith of an older program. I had also been unable to get Windows to add the program to the OpenWith list (I had been browsing to the program from within OpenWith). With Registry changes I fixed it on the first try, but it wasn't easy!

Apparently many have been plagued with this kind of problem, and a web search gives MANY articles that each suggest multiple ways (up to 13) to try to fix it. None worked for me. The problem seems to be most common with 3rd-party graphics programs.

SYMPTOMS: I could run the program from its icon on my desktop; but it always failed after right-clicking from my file manager (Dopus) into the OpenWith menu, in order to open it with a selected file loaded. Going to the .exe file in "Program Files (x86)" and checking the properties it was showing as an App instead of a program. I tried making compatibility settings, but they would not stick.

The program in question is Jasc's Paint Shop Pro 7, circa 2001. (I never liked the newer versions, and this meets my needs.)

Fortunately, I have two identical laptops (Lenovo E-560), of which I bought one years ago, which has an operating system migrated from older computers; from Win XP, to Win-7, to Win-10. I bought the second one used, inexpensively, recently (the old one will become my spare), and it had a fresh install of Win10. I installed PSP-Pro-7 on the new computer's fresh Win-10, from a second copy of the program. (Both machines are running Win10 22H2, 19045.3930).

A KEY CLUE: In a Youtube about the problem, I learned that especially for graphics programs, newer versions of Win10 are depreciating older graphics programs to emphasize using Apps built into Windows or available on the Microsoft Store. Also, somewhere someone said that the problem is rare on older computers where the problematic program has migrated along through updates to next big versions of Windows, but is common on fresh installs of Windows.

MY SUCCESSFUL EFFORT: Finding nothing online about how to fix this by editing the Registry, I dove in -- using the Registry of the old computer as a model. I searched for psp.exe, and F3'd on both computers until I found things that were different or missing. I made some changes along the way, avoiding differences that involved long hex strings in {curly brackets}, except for one that was intriguing. When done, I had success on the first try.

MAIN CHANGES MADE:

At the "find" below, my new computer had only two of the six highlighted entries in the first image below. Note that only two of these include the search term psp.exe, but all are "Jasc" entries (and fortunately were all grouped together). Both here and in other HKeys where the six cropped up, I added the missing four to the new machine.

Of course "OpenWith" keys cropped up several times (again in several HKeys). (See example in second image.) Each of these hits were for a specific file extension that had a subkey with psp.exe as its value or part of its value. I modified keys that had psp.exe in it, but with a lot of other garbage that must have flagged it as being disabled by the system, so that the values was just psp.exe. In the "MUIList" key in the example below, note its value "ba". This means that item b above it will be placed in the OpenWith menu ahead of item a (and the operating system will also add other items to the visible menu). You may see keys for some file extension that have subkeys with six or seven entries, and a MUIList like cdaefb, for ordering the menu.

No, I didn't. That would have been the next step, but it is essentially what I had already done on the new machine, with a first install.