Did you change the name of the parent class in C++?
If so you can “redirect” as shown here
Or in this video
If you are reading a null pointer (an exception) in the blueprint constructor (pure Blueprint → no C++) then you will never be able to open it again… you will have to delete the file.
It’s a good idea to use bluprint for everything you can’t do in C++, otherwise it’s better to use C++…
Among other advantages, when something like this happens you will never lose 100% of your work.
