How to get rid of BP Bug which makes BP invalid after UE4 Restart?

Hello,

ich have bug in BP for a few weeks. I know it is a bug, because that could not be a BP problem.

Every time I restart the UE4 engine, my character BP gets invalid and shows error. And every time I delete the nodes and make the same connection again, click compile, and then it works. I did it at least 15 times, so I am sure I do every time nearly the same.

I startet to delete nodes, and save on every step. I deletes also folders like Binaries and Intermediate, and build and compile everything again, but the error still come back after UE4 Editor Restart. And again, and again, after delete some BP nodes, rebuild it again, and connect it again as it was, it compiles again fine. :frowning:

Any idea how to get rid of such annoying bug in BP?

Bug occurs after changing some already existing and in BP used struct. But as I said, even after correct all BP nodes to the new structure, the BP gets every time invalid after UE4 Restart.

Every time something like this appears:

Can’t connect pins : Only exactly matching structures are considered compatible.

Best regards
Flow

Open Project Settings, search for Use Compilation Manager and turn it off. Recompile, save, restart editor.

Any better?

Can’t connect pins : Only exactly
matching structures are considered
compatible.

Unfortunately, structs are still deeply flawed. You can right click nodes and refresh them, this sometimes works with split structs that were updated and are causing problems or mark owning blueprints dirty.

Unfortunately, structs are still deeply flawed. You can right click nodes and refresh them, this sometimes works with split structs that were updated and are causing problems or mark owning blueprints dirty.

Yes, of course, at first try to fix that I had simply did “refresh nodes”. It also works, but only until I restarted the UE Editor, then the same error occurred. At the moment I try every time an other way for fix ing, refresh nodes, delete nodes, at nodes back again. But still the error comes back right now. :frowning:

Thanks for the tipp:

Open Project Settings, search for Use Compilation Manager and turn it off. Recompile, save, restart editor.
I will try that later. Thanks!

Unfortunately, structs are still deeply flawed
I thought structs are really good to structure code (structure BPs in my case) and get into a good system for maintaining all. Till now, I drive very good with structs. I hope they are not to buggy :frowning:

Open Project Settings, search for Use Compilation Manager and turn it off. Recompile, save, restart editor.

Thanks thousand times. When I read your tip, it sounds not really as a solution for me, but it worked!!! No I did nearly 20 times fixing the sames nodes, but now it seems to work event after Editor restart.

How did you know that? :slight_smile:
And should I set “Use Compilation Manager” back to ON? Or better let it off? It seems to make more problems as bringing better solutions.

It’s related to the engine version.

Your project was created before 4.17 and, at some point, you upgraded to 4.17 - this is the version that introduced the blueprint Compilation Manager. It’s a very clever tool but was somewhat flawed which Epic hinted at themselves in this post.

The Compilation Manager received major fixes in v4.18 and seems to be working fine. It might be a bit too early to tell, though. If you upgrade to 4.18, consider switching it back on again - it’s probably on as default anyway.