# I can't cook/package my game, and I can't really find the problem from the only 1 error. **URL:** \ **Category:** Programming & Scripting\ **Tags:** unreal-engine, crash, bug-report, question, Blueprint\ **Created:** [September 25, 2025, 3:43am UTC](https://forums.unrealengine.com/t/i-cant-cook-package-my-game-and-i-cant-really-find-the-problem-from-the-only-1-error/2659649 "2025-09-25T03:43:37Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![SteveLosive](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@SteveLosive](https://forums.unrealengine.com/u/SteveLosive)\ **Post date:** [September 25, 2025, 3:43am UTC](https://forums.unrealengine.com/t/i-cant-cook-package-my-game-and-i-cant-really-find-the-problem-from-the-only-1-error/2659649/1 "2025-09-25T03:43:37Z")
Hi everyone, I’ve been trying to cook/package my game for days now, and I can’t find and fix this error. I don’t really understand what’s the problem. I’m using UE5.6, and as a VFX artist I find it difficult to program, so I’m using Horror Engine which allows me to get as creative as I can get, without needing to code. Anyways, I’ve looked for `HorrorEngine.HorrorEngine_C` and I found they’re all Event Start, there are no errors when I compiled the BP, and all the nodes are connected perfectly. Plus `HorrorEngineSettings` isn’t even referenced directly, but settings within that BP is referenced, and it’s not connected directly to any of the Event Starts. Honestly, I’m not even sure that this is the reason why cooking fails every time. `LogProperty: Error: FStructProperty::Serialize Loading: Property 'StructProperty /Game/HorrorEngine/HorrorEngine.HorrorEngine_C:HorrorEngineSettings'. Unknown structure.` [cooking log.txt](https://forums.unrealengine.com/uploads/short-url/6iHSy49umi2XFE2rMUPbIm5U4y3.txt) (1.3 MB) [package log.txt](https://forums.unrealengine.com/uploads/short-url/pIYzVmlse3NnC9pfvZKywXFjKHN.txt) (2.3 MB) ---
**Author:** ![BRGEzedeRocco](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/brgezederocco/32/1216890_2.png) [@BRGEzedeRocco](https://forums.unrealengine.com/u/BRGEzedeRocco)\ **Post date:** [September 25, 2025, 4:52pm UTC](https://forums.unrealengine.com/t/i-cant-cook-package-my-game-and-i-cant-really-find-the-problem-from-the-only-1-error/2659649/2 "2025-09-25T16:52:42Z")
Hi @SteveLosive , I’ve been digging around the Unreal forums and found a few similar cases, maybe one of these solutions could help: People suggest checking struct variables and using **Refresh All Nodes** in the affected Blueprints > [@Packaging error due to Unknown Structure ?](https://forums.unrealengine.com/t/packaging-error-due-to-unknown-structure/1771123): > > Hey ! I’ve been trying to package my game but unfortunately an error has been coming up : UATHelper: Packaging (Windows): LogInit: Display: LogProperty: Error: FStructProperty::Serialize Loading: Property ‘StructProperty /Game/Inventory/Items/BP\_TestActor.BP\_TestActor\_C:LookAt:CallFunc\_GetDataTableRowFromName\_OutRow’. Unknown structure. UATHelper: Packaging (Windows): LogInit: Display: LogProperty: Error: FStructProperty::Serialize Loading: Property ‘StructProperty /Game/Inventory/UI/WBP\_Drag… In this post they fixed it by renaming the struct variable, recompiling and saving, or even recreating the struct from scratch > [@Unknown structure Error When Cook](https://forums.unrealengine.com/t/unknown-structure-error-when-cook/339325/11?page=3): > > I just encounter the same problem,and i googled it , i try to use a lot of methods, but it has not been resolved. at last , i renamed the struct. and build the project again. it was sucessed! you can try it. others solved it by opening the Blueprints that reference the struct, running Refresh All Nodes, and compiling. > [@Unknown Structure Error](https://forums.unrealengine.com/t/unknown-structure-error/2238831): > > Hi, When I try to package my project I get lots of unknown structure errors coming from something with data table row out rows. I don’t get any errors during runtime before packaging and I didn’t get these errors before upgrading the engine version (from 5.4 to 5.5). I can also tell the the path mentioned in the error is wrong, for example: “LogProperty: Error: FStructProperty::Serialize Loading: Property ‘StructProperty /Game/UI/Asset/UI\_Asset\_Widget.UI\_Asset\_Widget\_C:PopulateVariationBox:Ca… And lastly, this page explains why the error happens and the common steps to resolve it > **[Unreal Engine Tips: Fixing "Unknown structure" Packaging Error](https://unrealpossibilities.blogspot.com/2021/01/unreal-engine-tips-fixing-unknown.html)** > > A blog about video games & game design. Hope it helps! ---
**Author:** ![SteveLosive](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@SteveLosive](https://forums.unrealengine.com/u/SteveLosive)\ **Post date:** [September 25, 2025, 7:04pm UTC](https://forums.unrealengine.com/t/i-cant-cook-package-my-game-and-i-cant-really-find-the-problem-from-the-only-1-error/2659649/3 "2025-09-25T19:04:32Z")
Thank you so much, this is great info. I’ll try each and every possible fix until I get it to cook/package. ---
**Author:** ![SteveLosive](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@SteveLosive](https://forums.unrealengine.com/u/SteveLosive)\ **Post date:** [September 25, 2025, 7:49pm UTC](https://forums.unrealengine.com/t/i-cant-cook-package-my-game-and-i-cant-really-find-the-problem-from-the-only-1-error/2659649/4 "2025-09-25T19:49:28Z")
IT FRICKING WORKED!! THANK YOU!!! Refreshing the nodes does it, I opened the BP, went to file, then refresh all nodes and that did it. ---
**Author:** ![Simmoteph](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Simmoteph](https://forums.unrealengine.com/u/Simmoteph)\ **Post date:** [March 1, 2026, 10:07pm UTC](https://forums.unrealengine.com/t/i-cant-cook-package-my-game-and-i-cant-really-find-the-problem-from-the-only-1-error/2659649/5 "2026-03-01T22:07:14Z")
This worked for me. If you are experiencing this more than once then I suggest relying on a struct that isn’t made in Blueprints. (source: ChatGPT) FWIW, it likely happened to me because of a “Replace All”, where one struct replaced another, nearly identical, struct, resulting in uasset corruption.