One of the changes that were made from 8, 8.5 to 9 was that the files were scanned on opening again like they used to.
Not sure if that is your issue.
Try Saving a copy as Compact in 8 and then opening that new copy in 10.
I saved the file as Compact, tried to launch it but FM10 crashes immediately
So it is possible that there is an error in the file that FM8 doesn't see,
but FM10 does.
Can i 'debug' the file then?
Not really. I have sent you a private message ( check upper right hand side of window ).