Project crashes on startup

My project crashes on start up. I’m using blueprints and I made a macro with a math node inside. The expression is “round(x/10)10”.I saved and it crashed, and now it crashes on start up. Does unreal not have incremental saves?, I have a lot of work in this project.


We apologize for the inconvenience.
Please send this crash report to help improve our software.

BTW I’m using the latest update. 4.301?

Hi Redsett,

If you remove the macro expression from your project does it crash still? Can you please post your logs so I can have a look at what might be going on? Thank you!

Is there a way to remove the macro expression from the project without opening it?

If you know the filepath of the expression you can go into your project folders and pull the file manually. It should be located in the \UnrealProjects\PROJECTNAME\content\FOLDERNAME.

I found the blueprint that it is in, I assume that’s as far in as I’m going to get?

If you were able to pull the file that causes the crash and feel comfortable with it I’d be happy to take a look at it and see what might have occurred.

Yeah it opens fine without it. Here you go Adam! There’s only one macro in text

Hi Redsett,

Can you try to recreate the expression in a second macro and see if the crash occurs again? I am getting a crash on this end and would like to see if it is specifically a corrupted file or if it is the expression itself that I can test. Thank you!

Hi Redsett,

We have not heard from you in quite some time. I am marking this question as answered for tracking purposes. If you are still experiencing this, please comment here with the information requested. Thank you!

Hello there,
i’m having the same issue. Regardless of how easy the math expression is, the error is about “casting” failed, like it were trying to cast the mathe expression in some way.

Unknown exception - code 00000001 (first/second chance not available)

Cast of K2Node_MacroInstance //Game//Blueprints//BP_2D_Array_Int.BP_2D_Array_Int:GetElementAt.K2Node_MacroInstance_438 to K2Node_MathExpression failed

If I replace the expressions by the graph they represent it works fine without error. The error crash at startup appears if the blueprint was saved before compiling, so each time the blueprint is opened again, the editor crashes immediatly.

I’m using version 4.4.2.

Hi Xentrics,

Does this occur in a clean project with no additional content?

The original project was c++ compiled and therefore not clean.
But I created a new blueprint FPS project with the UE launcher and migrated ONLY the macro library there.
Then, I created a new blueprint that should use one of those macros defined in the library and added a math expression node like: (x*y) + z

Before adding that expression, it worked fine. Adding the expression caused the editor to collapse again with a similar error message.

It is safe to assume that the bug is reproduceable.


I realized something - I think I read something that a macro is not allowed to contain another macro inside of it ( or something like that ). Could that be the issue here?

Hi Xentrics,

I was able to reproduce this and am entering a bug report, TTP# 346745 to be assessed by our development staff. Thank you and have a great day!