Move project to a newer UE version

Could you please share your experience in moving a large project (whole game) to a newer version of UE.
I found that not everything can be migrated to a newer version (e.g. bleuprints).
So I am wondering if I have created a project, for example in UE4, and then decided to move to UE5, what problems will I face (for example, creating all blueprints from scratch).