What does "open gl output not supported" mean in Unreal?

Could anyone please tell me what this “Open Gl output not supported”?

I have also attached an image below.

In your case it means that a specific OpenGL debug extension is not supported on the platform your are executing this binary. If you wonder where the message comes from, it’s here: Engine/Source/Runtime/OpenGLDrv/Private/OpenGLDevice.cpp#L434

Basically it’s trying to execute NVidia/AMD specific glDebugMessageCallbacks, but because neither have been initialized, you get that message out.

Does this explain why some of my GUI are not being executed and refuse to come up on the phone?

I do not believe that debug extensions have anything to do with your GUI problem. These extensions are there to help with OpenGL debugging and would not be enabled in release builds but only during development and debugging. (https://www.opengl.org/registry/specs/ARB/debug_output.txt)

I would printf or UE_LOG a bunch of statements around the places where your GUI does not display and see where that gets you. It’s possible that something else is causing the GUI not to appear…

Thank you I shall try.

Also, where is the" add on clicked" option while using the Widget blueprint?

It does not appear for me and I have attached an image below.

Any help would be appreciated.