Help can't be provided without more information. You should invest more time to find out what items (functions, layouts, etc.) are involved when FileMaker crashes.
Recover not reporting an error is no guarantee that all elements as such are error free.
I would suspect a layout element to be the cause. To test this go to one layout after the other to see it shows OK. Next test all scripts (on a copy) whether one crashes.
Further check for plug-ins in the old version and whether they have a compatible equivalent in the converted solution.
Have you made a clone and re-imported the data?
You might want to show the suspected script.