# Compile Blueprint Crashes editor; (Virtual functions table is invalid)

**URL:** <https://forums.unrealengine.com/t/compile-blueprint-crashes-editor-virtual-functions-table-is-invalid/403910>\
**Category:** Blueprint\
**Tags:** inheritance, compiling, unreal-engine, crash, editor, Blueprint, question\
**Created:** [September 6, 2017, 5:17pm UTC](https://forums.unrealengine.com/t/compile-blueprint-crashes-editor-virtual-functions-table-is-invalid/403910 "2017-09-06T17:17:36Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![anonymous\_user\_145a181d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_145a181d](https://forums.unrealengine.com/u/anonymous_user_145a181d)\
**Post date:** [September 6, 2017, 5:17pm UTC](https://forums.unrealengine.com/t/compile-blueprint-crashes-editor-virtual-functions-table-is-invalid/403910/1 "2017-09-06T17:17:36Z")

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Hi Everyone,

I am using Unreal Engine 4.17.1 (both the GitHub source and the launcher versions). I am running into an issue that has me stumped. In the project that I am working on there is an actor class that we use as a parent to many other classes. This file has been in our project awhile and has had no issues. Recently we tried to change and compile it but this ends up crashing the editor. When we looked deeper into the issue, it looks like the event is triggered by a conditional statement in the UE4 source code. The statement is as follows:

```
if (*(void**)this == nullptr)
{
	UE_LOG(LogUObjectBase, Error, TEXT("Virtual functions table is invalid."));
	return false;
}

```

Does anyone know what could cause this, and how we could fix it?

Thanks!

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**Author:** ![anonymous\_user\_22864868](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_22864868](https://forums.unrealengine.com/u/anonymous_user_22864868)\
**Post date:** [September 6, 2017, 5:39pm UTC](https://forums.unrealengine.com/t/compile-blueprint-crashes-editor-virtual-functions-table-is-invalid/403910/2 "2017-09-06T17:39:50Z")

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I have been debugging this problem as well. If I start with my application in 4.16.2 i can compile all of the blueprints no issue. When I upgrade to 4.17.1 I can’t compile some of my actor classes. The only difference i can see is the get root component node (1) changed over to a K2 get root component node (2).

1. 

![212521-grc.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/7/a/7/7a7c8dedb70c2447393ab20a2f6418b83a2f2cef.png)

1. 

![212522-k2-get-root-component.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/6/e/e/6ee9ef1b946546b508c90b3a4a787e332dee9988.png)

I would just switch back but we have done development in 4.17.1 and it is saying that my level is not backwards compatible.

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<div class="post-metadata">

**Author:** ![anonymous\_user\_22864868](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_22864868](https://forums.unrealengine.com/u/anonymous_user_22864868)\
**Post date:** [September 6, 2017, 5:58pm UTC](https://forums.unrealengine.com/t/compile-blueprint-crashes-editor-virtual-functions-table-is-invalid/403910/3 "2017-09-06T17:58:12Z")

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Trying to switch back to version 4.16.2 i get this message:  
Failed to open map file. This is most likely because the map was saved with a newer version of the engine.

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<div class="post-metadata">

**Author:** ![anonymous\_user\_145a181d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_145a181d](https://forums.unrealengine.com/u/anonymous_user_145a181d)\
**Post date:** [September 11, 2017, 12:31pm UTC](https://forums.unrealengine.com/t/compile-blueprint-crashes-editor-virtual-functions-table-is-invalid/403910/4 "2017-09-11T12:31:24Z")

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I found a post, that solved my issue with a work around. [Thank you, Burnz]

you have set  
[/Script/UnrealEd.BlueprintEditorProjectSettings]  
bUseCompilationManager=False

Here is the link to the original post:  
[Editor crashing (4.17) when compiling Blueprints (UE-48429) - Blueprint - Epic Developer Community Forums](https://answers.unrealengine.com/questions/700562/editor-crashing-417-when-compiling-blueprints-ue-4.html)

If any one figures out the original issue, causing this to happen, or if there is another fix, please let me know.