I am not sure whether anyone on this support board is an expert on debugging FragPipe problems.
What program is shown in that screenshot?
The error that you are getting from MSFragger is not very helpful because the compiled code has been run through a "minimizer" which means that the names of things have been changed to be as small as possible. So, you're getting an error in a method which is now called "A.a". If we knew what the name of that method before it had been minimized, that would probably give us a good hint as to what is going on.
Where did you install your software from? It might be possible to find or build you a version of that software which gives better information when the error happens.