Bug 1299399 - "Failed to build EntityScene" bug

Edit: Not sure if my dead script was even the original cause. Submitted a bug report. Details here.

Hello, I just ran into this error. Here's a screenshot:



After a lot of confusion I eventually figured out what was causing it - I had deleted one of my authoring components that was currently on some of my prefabs that were referenced in the scene. So first off - it would be really great if we could get a more helpful error message for this. Clicking build and seeing the error message "Failed to build entity scene" as my only hint basically makes me want to uninstall Unity forever.

Anyways, aside from that I also ran into an issue with trying to get my builds to recognize that I had fixed the problem. I still have a pretty loose understanding about how conversion data gets cached so I'm only going to explain what occured and how I fixed it, whether it's a bug or this is how it's supposed to work, I have no idea. I want to be very clear that I made NO ACTUAL CHANGES to my project between these steps aside from the mentioned attribute changes.

Step1 : Replace the dead scripts with new authoring scripts and save the prefabs.
Step2 : Attempt dotnet build - same error.
Step3 : Add a "ConverterVersion" attribute to my new authoring script that I just added, with a version of "1".
Step4 : Attempt dotnet build - same error.
Step5 : Increment the converter version to "2".
Step6 : Attempt dotnet build - success!
Step7 : Attempt wasm build - same error <- This doesn't seem right to me? Surely incrementing the version should have fixed it for both builds?
Step8 : Increment the converter version AGAIN (even though I didn't actually make any changes) to "3".
Step9 : Attempt wasm build - success!

So yeah. Hopefully we can get a better error message for this case, or at least this might save someone from some pointless debugging.

 

Nevermind. After working on my project for a while I tried to build again and I'm getting the same error. I'd love to know how I can fix this.

 

Just hit this again. The previous times it happened I was able to get it to go away by incrementing the converter version on one of my authoring scripts, now that is not working.

All of my conversion happens in

IConvertGameObjectToEntity

scripts. They're all pretty basic, most do nothing more than add a component. This is the one I was referring to from the original post:

Code (CSharp):

1. using TinyRogue;
2. using Unity.Entities;
3. using UnityEngine;
4.  
5. [ConverterVersion("PathBlockerAuthoring", 5)]
6. public class PathBlockerAuthoring : MonoBehaviour, IConvertGameObjectToEntity
7. {
8.     public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem)
9.     {
10.         dstManager.AddComponent<PathBlocker>(entity);
11.     }
12. }

It looks like it's showing a null reference exception, I'm not sure what to parse from this though:

Code (CSharp):

1. Launched and connected shader compiler UnityShaderCompiler.exe after 0.03 seconds
2. System.NullReferenceException: Object reference not set to an instance of an object
3. This Exception was thrown from a job compiled with Burst, which has limited exception support. Turn off burst (Jobs -> Burst -> Enable Compilation) to inspect full exceptions & stacktraces
4. (Filename:  Line: -1)
5.  
6. Exception thrown during SubScene import: System.NullReferenceException: Object reference not set to an instance of an object
7.   at Unity.Entities.EntityRemapUtility.RemapEntity (Unity.Entities.EntityRemapUtility+EntityRemapInfo* remapping, Unity.Entities.Entity source) [0x00000] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Entities\EntityRemapUtility.cs:45
8.   at Unity.Entities.EntityRemapUtility.RemapEntity (Unity.Collections.NativeArray`1[Unity.Entities.EntityRemapUtility+EntityRemapInfo]& remapping, Unity.Entities.Entity source) [0x00000] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Entities\EntityRemapUtility.cs:40
9.   at Unity.Entities.EntityRemapUtility.PatchEntities (Unity.Entities.EntityRemapUtility+EntityPatchInfo* scalarPatches, System.Int32 scalarPatchCount, Unity.Entities.EntityRemapUtility+BufferEntityPatchInfo* bufferPatches, System.Int32 bufferPatchCount, System.Byte* chunkBuffer, System.Int32 entityCount, Unity.Collections.NativeArray`1[Unity.Entities.EntityRemapUtility+EntityRemapInfo]& remapping) [0x000ac] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Entities\EntityRemapUtility.cs:244
10.   at Unity.Entities.Serialization.SerializeUtility.SerializeWorldInternal (Unity.Entities.EntityManager entityManager, Unity.Entities.Serialization.BinaryWriter writer, System.Object[]& referencedObjects, Unity.Collections.NativeArray`1[T] entityRemapInfos, System.Boolean isDOTSRuntime) [0x003d5] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Entities\Serialization\SerializeUtility.cs:566
11.   at Unity.Scenes.Editor.EditorEntityScenes.WriteEntityBinary (Unity.Entities.EntityManager scene, Unity.Scenes.ReferencedUnityObjects& objRefs, Unity.Collections.NativeArray`1[T] entityRemapInfos, System.String entitiesBinaryPath, Unity.Scenes.Editor.WriteEntitySceneSettings writeEntitySceneSettings) [0x00068] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\EditorEntityScenes.cs:655
12.   at Unity.Scenes.Editor.EditorEntityScenes.WriteEntitySceneSection (Unity.Entities.EntityManager scene, Unity.Entities.Hash128 sceneGUID, System.String subsection, UnityEditor.Experimental.AssetImporters.AssetImportContext importContext, Unity.Scenes.Editor.WriteEntitySceneSettings writeEntitySceneSettings, System.Int32& objectReferenceCount, Unity.Scenes.ReferencedUnityObjects& objRefs, Unity.Collections.NativeArray`1[T] entityRemapInfos) [0x0005a] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\EditorEntityScenes.cs:580
13.   at Unity.Scenes.Editor.EditorEntityScenes.WriteEntitySceneInternal (Unity.Entities.EntityManager entityManager, Unity.Entities.Hash128 sceneGUID, System.String sceneName, UnityEditor.Experimental.AssetImporters.AssetImportContext importContext, System.Int32 framesToRetainBlobAssets, System.Collections.Generic.List`1[T] sectionRefObjs, Unity.Scenes.Editor.WriteEntitySceneSettings writeEntitySceneSettings, Unity.Entities.Conversion.ConversionJournalData& journalData) [0x00359] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\EditorEntityScenes.cs:361
14.   at Unity.Scenes.Editor.EditorEntityScenes+<>c__DisplayClass11_0.<ConvertAndWriteEntitySceneInternal>b__0 (Unity.Entities.World conversionWorld) [0x00046] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\EditorEntityScenes.cs:189
15.   at Unity.Entities.GameObjectConversionUtility.ConvertScene (UnityEngine.SceneManagement.Scene scene, Unity.Entities.GameObjectConversionSettings settings) [0x00048] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Entities.Hybrid\GameObjectConversion\GameObjectConversionUtility.cs:258
16.   at Unity.Scenes.Editor.EditorEntityScenes.ConvertAndWriteEntitySceneInternal (UnityEngine.SceneManagement.Scene scene, Unity.Entities.GameObjectConversionSettings settings, System.Collections.Generic.List`1[T] sectionRefObjs, Unity.Scenes.Editor.WriteEntitySceneSettings writeEntitySettings) [0x00092] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\EditorEntityScenes.cs:199
17.   at Unity.Scenes.Editor.SubSceneImporter.OnImportAsset (UnityEditor.Experimental.AssetImporters.AssetImportContext ctx) [0x001c7] in C:\Users\sark\Documents\unity\tinyrogue\Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\SubSceneImporter.cs:154
18. UnityEngine.DebugLogHandler:Internal_Log(LogType, LogOption, String, Object)
19. UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[])
20. UnityEngine.Logger:Log(LogType, Object)
21. UnityEngine.Debug:Log(Object)
22. Unity.Debug:Log(Object) (at Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Entities\Stubs\Unity\Debug.cs:17)
23. Unity.Scenes.Editor.SubSceneImporter:OnImportAsset(AssetImportContext) (at Library\PackageCache\com.unity.entities@0.16.0-preview.21\Unity.Scenes.Editor\SubSceneImporter.cs:167)
24. UnityEditor.Experimental.AssetImporters.ScriptedImporter:GenerateAssetData(AssetImportContext)
25. (Filename: Library/PackageCache/com.unity.entities@0.16.0-preview.21/Unity.Entities/Stubs/Unity/Debug.cs Line: 17)
26.  
27. -> (target hash: '74eb1d22cb084ac89b1966c50b878704') in 4.263658 seconds
28.   Import took 4.275836 seconds .

 

This time I got it to go away by enabling a disabled gameobject in my scene, doing a build, then re-disabling it. And to re-iterate, in this case incrementing the ConverterVersion of an authoring script that was in my scene did nothing.

 

This keeps popping up. No matter how much I try to narrow it down, it really just seems completely random. At this point I'm not even sure if my dead script issue was the actual original cause.

Not sure what I'm doing wrong but if I see this error one more time I'm going to lose my mind, so I created a bug report and I'll leave the project be for now. I tried to create a smaller repro case but I couldn't recreate it, so I just submitted the whole project. Case # 1299399.

 

So I was under the assumption that doing a MemClear on a buffer of entities would be the equivalent of setting all the elements of the buffer to Entity.Null. Or in other words, doing a memclear on a buffer of structs would be the equivalent to setting every element of a buffer to "default". I'm far from an expert on "unsafe" stuff so I'm honestly not sure.

Continuing with that assumption though, after looking at it I realized there was a bug in my MemClear code - I was failing to account for the size of the elements in the buffer. I wrote a test that seems to align with my assumptions:

Code (CSharp):

1.     [Test]
2.     public void MemClearSuccess()
3.     {
4.         var em = EntityManager;
5.  
6.         var e = em.CreateEntity();
7.         var buff = em.AddBuffer<SomeBuffer>(e);
8.  
9.         buff.ResizeUninitialized(400);
10.         unsafe
11.         {
12.             UnsafeUtility.MemClear(buff.GetUnsafePtr(),
13.                 buff.Length * UnsafeUtility.SizeOf<SomeBuffer>());
14.         }
15.  
16.         for(int i = 0; i < buff.Length; ++i)
17.         {
18.             Assert.AreEqual(Entity.Null, buff[i].entity);
19.         }
20.     }
21.  
22.     [Test]
23.     public void MemClearFail()
24.     {
25.         var em = EntityManager;
26.  
27.         var e = em.CreateEntity();
28.         var buff = em.AddBuffer<SomeBuffer>(e);
29.  
30.         buff.ResizeUninitialized(400);
31.         unsafe
32.         {
33.             UnsafeUtility.MemClear(buff.GetUnsafePtr(),
34.                 buff.Length); // Not accounting for size of buffer elements
35.         }
36.  
37.         for (int i = 0; i < buff.Length; ++i)
38.         {
39.             Assert.AreEqual(Entity.Null, buff[i].entity);
40.         }
41.     }

The first test passes, but the second test fails since (I assume, again not an expert on this stuff) that it's only clearing part of the buffer and leaving garbage memory in the rest.

Either way, fixing up the memclear code seems to have fixed the bug though! And if it fails again I can just revert to initializing the buffers at runtime like you suggest. Thanks a lot for looking it this, I'm excited to be able to dive back into Tiny!