Still seeing the problem in UE5.0.3.
- I just followed through the Programming Quick Start for Windows exactly, though Live Coding was enabled, so built via Ctrl-Alt-F11 in the editor rather than in VS 2019.
- Saved All and quit
- Later re-opened the project
- Got the same error as OP (except for the Mesh component of the FloatingActor the tutorial has you create).
I resolved the error using xKuusi’s steps above, and it does not recur. Also thankfully UE didn’t make me have to re-place an instance of the Actor.
Seems like it could be related to Live Coding compilation? I realize that only makes sense back to v4.22 though…
I repeated the above with a second brand new C++ Actor subclass, built with Live Coding, placed an instance of it it in the level, and got the same error for that Actor instance after re-opening the project.
I then disabled Live Coding in Editor Preferences, created a third new C++ Actor subclass, built in VS 2019, placed an instance, and did not see the error when re-opening.
Need to explore the output of Live Coding more in detail to see what the difference might be. The good news is that you can still use Live Coding, just so long as you eventually do a build without it.