Hi, I also got this error when testing migrate from 5.5.4 to 5.6.0
You could try to do Find All node GetEnumeratorNameAsString used in all BP in original project 5.5.4, then remove them temporarily, then recreate the node in 5.6.0
Idk why but it causing that error crash, at least that’s what happen in my project and removing them temporary is fixed the crash.
Other than this error, I got the other one which is from Nanite skeletal mesh, I’m not sure if it’s related or not, but if you’re using Nanite skeletal mesh you could try to disable them.
I think 5.6.0 is missing Nanite skeletal mesh from 5.5.1+, iirc it was causing error in 5.5.0