"one or more blueprints has an unresolved compiler error", except they don't

Every time I start the editor, open a specific level and try to play in editor, this message appears to me:


And every time, I just open to these blueprints, click “Compile” and that’s it. It compiles without errors and now I can play in editor like nothing happened. Until I restart the editor, then I have to do the same thing. Again and again.

How can I fix that?


Two screenshots of the blueprint before compile (edit 2: first, I though that there weren’t any other information, but I was wrong: when hovering the mouse cursor over the error, a message appears):

And here is a screenshot after click the “Compile” button:

See? There isn’t any error. It’s just annoying. Every time I restart the editor, I have to open these blueprints and recompile…

After you compile them are you saving them?

They are not marked as dirty, so I don’t have anything to save. But I clicked the “save” button anyway, after compile, just to be sure. Didn’t work.

Does anything get marked with a note or error before you compile? What is causing the dirty tag to fire? Have you checked your log files for any clue?

Try restart the editor (obviously). If it still does it, remove the /saved and /intermediate folders in your project (back them up).

PS: there is probably a compiler error still.

The error happens when I restart the editor… how a restart would fix that? :stuck_out_tongue:

Anyway, I already removed Saved, Intermediate and Binaries folders, but it didn’t work.

Yes, each blueprint has a node marked with a red “ERROR” when I start the editor. When I compile, it disapears and everything works fine. I updated the post with new screenshots of this. I can’t see anything in the Message Log window, there is another place where I can check?

Ok is that variable coming from a CastTo node? if so what BP is it coming from? Have you checked that BP or recompiled it and saved it as well?

Hello Marcio Daniel,

I have a few questions for you that will help narrow down what issue it is that you are experiencing.

Quick questions:

  1. Can you reproduce this issue in a clean project?
  2. If so, could you provide a detailed list of steps to reproduce this issue on our end?
  3. Could you provide screen shots of any other bluerpints/settings that may be involved with this issue?
  4. Could you try hovering over the error with your cursor to see what error it is giving?
  5. Could you ensure that you do not have any circular dependencies?
  1. No, I can’t. I have no idea how and why it happens.
  2. There are just these two. I added new screenshots to the original post.
  3. First, first, I though that there weren’t any other information, but I was wrong: when hovering the mouse cursor over the error, a message appears. It’s the message on the third screenshot.
  4. Uhm, it actualy has circular dependencies. It compiles and works well after I click the Compile button, but it has. Blueprint A creates a new instance of blueprint B, and B has a reference to A.

Actually yes, the variable comes from a cast node.

Additional questions:

  1. Are the blueprints that have the circular dependencies the ones having the errors?
  2. If so, could you move those blueprints to a blank project and let me know if the error still occurs?

Hello Marcio Daniel,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will follow up.


Hi Rudy. I’m still have the error, but since it doesn’t appear easy to fix, I prefer to live with it. It’s annoying, but at least it works. If you think it deserves some research, Adam Davis already have access to the GIT repository of this project (I gave him access for some investigation related to another issue) and I can give more details, like the steps to reproduce.

I have this problem as well. I tracked mine down to a macro I use that includes a wildcard variable. Any blueprint that uses this macro needs to be recompiled every time I start UE.

For what it’s worth, the reason I use this macro is because Select doesn’t (or didn’t) “short circuit” - i.e., all inputs of the select evaluate instead of just the selected one.

I had something similar to your problem. One of my blueprints would always show an error after starting the editor, but making it compile would fix it.

The way I fixed it was finding the nodes that had the red ERROR! message below them, going into their blueprints and renaming the offending variables / functions, compiling and then renaming them back to their original name. Sounds weird, but worked for me.

I can confirm that this trick solves the problem for me. Thanks!