Remove interface output cause compile error in implemented class

Tested Engine version. 4.8.3, 4.9.

In blank project, without starter content

Steps:

  1. Add new blueprint interface class IManager
  2. Add new blueprint class manager
  3. Set Implemented Interface IManager in manager
  4. Add interface function MyFunction with 1 output (any types is ok), and compile the IManager
  5. Remove the previous added output in IManager::MyFunction
  6. Compile the manager will always display compiler error :

Error Graph named ‘MyFunction’ already exists in ‘manager’. Another one cannot be generated from (none)

The only way I can solve the error now is:

Remove the implemented interfaces “IManager” in manager, and then delete the function MyFunction.

Re-add the IManager as interface to manager.

Hi windkey,

I was able to reproduce this on my end and have entered a bug report, UE-20787, to be assessed by the development staff.

Thank you!
Waiting for your good news.

Hello, may I ask the bug status? Thank you.

Hi windkey,

This bug is still under assessment. Unfortunately I do not have a timeframe of when a fix will be made available.

Still there in 4.10.4.

Hi mxnko,

I checked on UE-20787 and it is still under assessment by the development staff. I do not have a timeframe of when a fix will be implemented, but I have updated the bug report to reflect that additional developers are experiencing this error.