Multiple TOptional errors while building

Development Programming & Scripting C++
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1

Hi,

I have just created my first ue5.5 project as a Blueprint project, then added a C++ class via the editor. Now, when I try to build the project, I get LOTS of errors of “incomplete type” with TOptionals, such as:

incomplete type "TOptional<FString>" is not allowed
incomplete type "TSlateBaseNamedArgs<SGenericDialogWidget>" is not allowed

errors
errors1649×591 53 KB

Those errors happen in the Engine files, like Dialogs.h, World.h, etc.

Any idea on how to fix that?

Thanks!

2

I’m having the exact same issue from a source build UE5.5 following the UE documentation for EOS. Not sure if its a bug and when it will be addressed.

image
image1010×381 46 KB

3

Exactly the same thing happened to me.
Started with the FPS template with C++. Clicked “Add C++ class” in the editor. Then added a property to my actor class.
Now the solution won’t build with lots of "incomplete type “TOptional<…” errors.