Steps:
Create an interface with a function
List item. Add an output to that function
Add that interface to a blueprint
Remove the output from the interface’s function
A bug occurs which prevents compiling
I’ve been able to fix it by removing the interface from blueprints that use it, then deleting all bugged functions within the interface, recreating them and then adding the interface again.
Hello Fistoflove,
This issue already exists in our system as UE-13335. Thank you for your report, and for posting your workaround.
Have a great day,
Sean Flint
Still encountering this (version 4.10.2) - just for renaming an output variable inside a blueprint interface function.
Given that readding the interface (breaking everything which uses it) seems to be the only solution, my current recommendation is that for whatever functionality you are using the blueprint interface, contain it all within a separate function, so that the process of readding is simply connecting up the pins between the function and the interface in each blueprint using it (which is still a massive amount of work).
Outside of that, either lock down every variable and every variable’s name in advance of using the function, or avoid using blueprint interfaces entirely.
Restarting the editor seems to fix being unable to readd a previously removed BPI.
This issue has been marked as fixed for 4.11. Give it a shot in the 4.11 Preview, as it should be resolved in that version.