UE5 [Source Build] Load Error "Field Type UberGraphFrame does not exist"

Hi you have to modify the assets/blueprints in UE4.26, NOT UE4.27 before moving to UE5
Firstly though you need to test with my latest GitHub Fork for UE5
(Visual Studio 2022 RC 2 builds and runs UE5.0) to see if you get the same errors

If this when built still does not work then you need to convert Blueprint to C++ in version 4.26 which will then compile in UE5 as no blueprint conversion takes place.

How To Convert a Blueprint Unreal Project to C++ (rhycesmith.com)

Now its compiled you can convert it back with the answer from here
How To Convert a C++ Unreal Project to Blueprint (rhycesmith.com)
I am not that clever on blueprints my skill is in C++

The final release of VS2022 come out on 8th November 2021, and I am assured that VS2022 will be the Official Build system for UE 5 as MS and UE have fixed the problems in UE 4.27/VS2022 builds. VS2022 will only compile UE4.26 if its the only VS compiler on your system.

I would be keen to know if its works for you on my ue5 fork