Bug report. TRASHCLASS, Target must have a connection problem

Development Programming & Scripting
1

This is a known issue and Epic is working on a fix :slight_smile:

2

Hi!

I want to report a bug in UE editor. This is not really a new bug, as I know, somebody already expected the same problem, you can read some info here - 4.9 Import Broke Parent-Child Relationship - Blueprint - Unreal Engine Forums BUT, as I can see this bug is not solved yet, so what I want to do - is to post here my problem details, - maybe this will help to deal with it.

First of all THIS BUG IS HARD TO REPRODUCE, because project may work normally for long time, but in one sunny day you’ll get an error message. I’m expecting this problem second time with the same project. First time I’ve just recreated the project, but for now my project is BIG enough, and re-creation will take LOTS of time, so, I hope UE dev team can handle this bug.

So, enough of blah-blah - here is a situation.

  1. I have a blueprint called, in example, Car based on Object class. This Car blueprint has a Drive pure function (I don’t know is this bug also appears in non-pure functions.)

  2. I’m creating a derived blueprint, in example Ferrari and override Drive function.

  3. Working … Working many many days. Hard working…

  4. Bam! Error message on editor startup while trying to play the game. Look at the picture.

90541-error-1.jpg

  1. Okay… Lets deal with that dammit errors.

90542-error-2.jpg
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  1. So, I really don’t know why editor can’t find Drive function (especially when it worked for so many days!)

  2. What I do is just delete the Drive function node, drag and drop Drive function from left panel Functions, reconnect pins, press compile and it works fine! Also I do this for all blueprints with this error.

  3. Now I can work and play!

  4. Then I’m closing the editor. Open it again and get the same error. Now return to step #5.

So my everyday work is now starting from steps #5-8. Ok, It’s not a really big problem - it’s SUPER-ANNOYING, but I can live with it. But what in some other sunny day the same error will appear in other blueprints too? Or editor just will unable to compile anything… and don’t even want to think about it…

Also, when I’m just trying to compile class Car (without handle that error in derived Ferrari blueprint first,) editor crashes with such a screen and error files that I’ve archived for you.

[Archive with error files][3]

[Copy-paste from error on screen below][4]

90544-error_screen.jpg
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I think that key to the problem is somewhere in this line from copy-paste:

UBlueprintGeneratedClass::GetAuthoritativeClass: ClassGeneratedBy is null. class '/Engine/Transient.TRASHCLASS_RoomSide_72’

Transient.TRASHCLASS_RoomSide_72 is a parent class - it’s a Car (Transient.TRASHCLASS_Car_72) in my example ))

This bug was on 4.11 and now it’s 4.12 Preview 3 as well.

So, that’s all I have to say for now. If you can handle this - this will be really cool.

Thanks for your work!

Roman.

3

Hmm… It’s good to hear that Epic already know about this pretty thing. I’m really hope they can handle this.