In regards to the Studio 12.4 and 12.5 issue, check in your Customer Portal to see if you have MFDC 12.6 available.  If not, try opening an SR to see if support can get you a copy, it's in the process of being released.

I was able to get a copy via my software portal earlier in the week, but the customer I was  working with did not have it yet.  If I had to guess, it would likely resolve the Windows 1909 issue, though I have yet to test 1909 with MFDC.

In regards to building the Apps, this is sometimes necessary when Windows changes underlying security.  It tends to be uncommon, but you can actually open the Virtual EXE directly in Admin Studio and then just tell it to rebuild.   Quite a quick process.  

I don't have any issue launching either Studio 12.5 or 12.6 on a freshly Built Windows 10 1909 System.

Not sure if an OS Upgrade could have broken studio, though I've never seen that in the past.

In regards to Win10 OS Upgraded requiring Virtual Apps to be rebuilt,  the first time this was widely seen was with 1803 needing MFDC at least 12.3.  Prior to that, even virtual apps many years old predating when the product was called ZAV vs MFDC were still working.  1903 did seem to cause some issues needing MFDC 12.5, but there were less reported issues around that....not sure why.

I would expect Win1909 to have any extra issues, since it should be the same as 1903 under the hood with a few added feature w/o any changes to the core OS itself with all 1903 and 1909 patches being the exact same files..... 

With a clean install of Windows 1909, I can't get 12.5 to launch (I get the .net error).  12.6 is not available to me in my Customer Center - Software yet.  I'm going to reach out and see if it can be made available.

Thanks!

As soon as you get an SR #, just tell them to send it my way and send me the # in a Private Message

Took a bit, but thankfully I've got access to 12.6 and it launches!

Is there a way to reprocess the containerized programs (the .exe output) so that they launch in this version of windows without having the .xappl or .svm that I'm not seeing?

Thanks!

Yup...It's quite easy when you know the trick...

In Studio where you can select a XAPPL or SVM to import, you can change it to *.* and select the virtual .EXE

It will import just the same and let you recompile it using 12.6

Thanks Craig!