Unknown structure Error When Cook

Development Programming & Scripting
41

Renaming the struct and then reseting the engine solved the problem for me.

42

Problem still here in UE5 : nothing above works for me
Do we have to stop using blueprint structs ?
Or maybe this doesn’t happen with c++ structs?

43

tried:

  1. duplicate struct
  2. delete & auto replace reference with duplicate
  3. everything breaks
  4. after repair and engine restart, error is gone.
  5. modified a default value of the fresh struct … and the error is back again …
1 Like
44

Hard to believe this is still an issue after 7 years. I was looking at https://issues.unrealengine.com/ to vote on it, and didn’t see a issue for it. Am I missing something?

45

In case someone meet this issue.

I met in in 4.27.2.

Just enetered in the blueprint which used the struct and in “file” I have refresh all nodes.

Saved and closed the eidtor.

Once I have reopened it the problem was solved and no erro were displayed in the log.

3 Likes
46

Upgrading a project from 5.0.3 to 5.1, none of these work.
I’ve encountered and fixed this error endlessly over the years, but 5.03 to 5.1 there is nothing I can find to make it work. In fact, trying any of these traditional fixes now create 1000x the errors. I’ve never seen so many red errors in a log before, from a perfectly clean building project in 5.0.3. Smh.

Please people, use source control, or this attempt to upgrade would 100% be the death of this project.

47

best solution i found was to move your struct to c++.

48

Still an issue in 5.2.1, amazing.

Still having random builds fail - having to go and add then remove a dummy variable from the class that doesn’t know the struct.

When it is 40 minutes to a build, time really adds up as this happens a dozen+ times a month.

49

This seems to be able to happen when you delete/move/change something that has any relationship at all with that struct. But what has always ended up solving the problem for me is to find those nodes in your blueprint (that your error threw), right clicking them and selecting Refresh Node.

1 Like
50

Thanks! Renaming/moving structures works perfectly. I spend hours on this :grinning:

51

Still an issue in 5.3.1.
In my case, when I recompiled the blueprint of the problem, the packaging was completed.
However, this does not mean that the editor shows compilation errors.

52

THANK YOU THANK YOU THANK YOU!!! deleted and remade struct and i got it to build! i was so worried!

53

This video is also useful for Unknown Structure issue: https://www.youtube.com/watch?v=aMGEqsGIrcI&ab_channel=TechNova45

1 Like
54

It worked to me, too!! Very nice!

55

Thanks for the tip. Simply closing and reopening Unreal after making a blueprint structure change is saves a bunch of time. Only 5 minutes wasted each time instead of the 20+ manually modifying all the chain saved blueprints.

It would be great if the underlying issue was fixed within Unreal, this is such a obvious and reproducible issue.

1 Like
56

OK, so the error passed and my build even have 0 warnings now, the issue for me was having an
wrongly implemented interface

Error looked like this:
LogProperty: Error: FStructProperty::Serialize Loading: Property ‘StructProperty /Game/Blueprints/TileMaps/Sky_Hill.Sky_Hill_C:EquipItem:ItemInfo’. Unknown structure.
LogProperty: Error: FStructProperty::Serialize Loading: Property ‘StructProperty /Game/Blueprints/TileMaps/Sky_Hill.Sky_Hill_C:ExecuteUbergraph_Sky_Hill:K2Node_Event_ItemInfo’. Unknown structure.

I entered the “Sky_Hill.Sky_Hill_C” Tilemap Actor and removed an implemented interface from it.
(which was unused, what probably caused the issue)

Good luck all.

57

Fix for 5.4.1

I just refresh nodes for those marked red on output error instead deleting the whole struct

2 Likes
58

Thank you! This worked to me!

59

thankyou that’s work for me