Assertion failed: Blueprint != NULL

Development Programming & Scripting Blueprint
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1

Hi guys,

When I open a blueprint in the editor, either it’s a blank blueprint or one from the starter content, the editor crashes every time. On the next start the editor offers to restore the assets (the blueprints I tried to open) and successfully opens the blueprint editor with assets. Any attempt to open another blueprint results in a crash.

In the log of my project I found a message that the engine crashed due to a failed assertion. This is a chunk from the log:

 [2014.04.13-07.38.57:379][349]LogWindows:Error: appError called: Assertion failed: Blueprint != NULL [File:F:\dev\github\UnrealEngine\Engine\Source\Runtime\Engine\Private\SimpleConstructionScript.cpp] [Line: 139]

Here is the complete log with the call stack.

Before I start debugging the engine, could anybody give me a quick & dirty tip how to fix the problem?

2

That is odd, certainly not something that should be happening. Is this an installed version, or one you built yourself from GitHub? Have you modified the engine in any way?

3

Hi

I built the engine myself from the master branch a week ago. No changes to the sources have been made.

4

Hi duburlan,

Does this issue occur in every project, including new template projects and were any errors reported when compiling in Development Editor? Thank you!

5

Hi ,

The issue occurs in every project, including a Blank one. No errors and warnings while compiling.

6

An ugly hack.

Commented out line 139 “check(Blueprint != NULL);” in SimpleConstructionScript.cpp and no crushing so far.

The UBlueprint* Blueprint variable from void USimpleConstructionScript::PostLoad() which causes “assertion failed: Blueprint != NULL” seems not being used by anyone in the function (except the check macros). I debugged the editor to figure out why is it NULL, but the code was so complicated (honestly, I have never run such a big project) and I didn’t learn much. One thing I noticed, that the variable Blueprint derived NULL from UObject* GetGeneratedBy field of UClass. I went to the declaration of this field and read the comment “This is the blueprint that caused the generation of this class, or NULL if it is a native compiled-in class”. Bug or it is really can’t be a compiled-in class?

Initially I wanted to put here some chunks of code from Unreal Engine, but I’m not sure guys from Epic Games would like it. Can I do so?

7

Hi duburlan,

We allow up to 30 lines of code to be shown for discussion, any more than that is not permitted. Did this crash start occurring after you created a new blueprint or has this occurred since installing the editor?

8

Hi ,

I’m not sure it started right after creation of a new blueprint, but I remember I could open and edit blueprints without crashing. Now when I open either level or class blueprint there pops up a window saying “Loading file: ActorMacros.uasset”, the editor freezes for a while and crushes.

Update: I went to my Engine\Content\EditorBlueprintResources\ and found out that my ActorMacros.uasset was modified three days ago… I don’t know by which means it got modified, can’t remember I was doing something unusual with the editor. So after replacing this file with one from the GitHub repository it’s not crushing, even with the uncommented check macros in SimpleConstructionScript.cpp.

Update2:: I created a new blueprint, saved the project and restarted the engine, but the file has not got modified.

Thank you for your assistance!

9

Yes, now it’s OK.

10

Hi duburlan,

Just to be sure, you are no longer experiencing the crashes now that you have removed the macro? If so, this asset may have been corrupted.

11

Excellent news! I will mark your answer that you found as accepted, if you have any more trouble out of this please feel free to continue the conversation as we will help you further. Have a great day!