webgl JS error

I tested a existing project that worked in unity 5.3.1p2.
Nothing changed, just a build in the new beta. (5.4.0b2)
The scene load 100%, and i can see the first frame in the background of the error.

Spoiler: error

Code (CSharp):

1. An error occured running the Unity content on this page. See your browser's JavaScript console for more info. The error was:
2. uncaught exception: abort(116) at jsStackTrace@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1057:12
3. stackTrace@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1071:21
4. abort@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1997170:43
5. nullFunc_viiiiiii@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:15162:2
6. b116@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1943667:2
7. __ZN9GfxDevice22GetDefaultVertexBufferE26GfxDefaultVertexBufferTypej [GfxDevice::GetDefaultVertexBuffer?2()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1206501:2
8. __Z30AddDefaultStreamsToMeshBuffersR9GfxDeviceR11MeshBuffersRK16DrawBuffersRangejj [AddDefaultStreamsToMeshBuffers(unsigned int&&&, unsigned int)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1451369:5
9. __ZN17GenericDynamicVBO17DrawChunkInternalERK21DynamicVBOChunkHandleRK14ChannelAssignsjP17VertexDeclarationR16DrawBuffersRangej [GenericDynamicVBO::DrawChunkInternal(unsigned int&&, unsigned int&*)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1359999:2
10. __ZN10DynamicVBO9DrawChunkERK21DynamicVBOChunkHandleRK14ChannelAssignsjP17VertexDeclarationPKNS_10DrawParamsE [DynamicVBO::DrawChunk?S(unsigned int&&, undefined?N?**)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1396611:2
11. __Z37ParticleSystemRenderer_RenderMultipleRK15RenderNodeQueueRK18RenderMultipleDataRK14ChannelAssignsb [ParticleSystemRenderer_RenderMultiple(bool&&&)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:753374:8
12. __Z29ParticleSystemRenderer_RenderRK15RenderNodeQueuejRK14ChannelAssignsi [ParticleSystemRenderer_Render(unsigned int&, int&)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1716289:2
13. __ZN13BatchRenderer5FlushEv [BatchRenderer::Flush()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1304698:13
14. __ZL20ForwardRenderLoopJobPN21GfxDeviceAsyncCommand10ArgScratchEPKNS_3ArgE [ForwardRenderLoopJob?S(GfxDeviceAsyncCommand::ArgScratch*, undefined?N?*)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:227702:5
15. __ZN9GfxDevice12ExecuteAsyncEPFvPN21GfxDeviceAsyncCommand10ArgScratchEPKNS0_3ArgEES2_S5_R8JobFence [GfxDevice::ExecuteAsync?S(undefined?F?*, void, GfxDeviceAsyncCommand::ArgScratch*, undefined?N?*)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1851854:2
16. __ZN23ForwardShaderRenderLoop16PerformRenderingER8JobFencePK11ActiveLightRK14ShadowCullDatabbbi [ForwardShaderRenderLoop::PerformRendering(bool&*&, bool, bool, int)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:393120:2
17. __Z25DoForwardShaderRenderLoopR17RenderLoopContextR13dynamic_arrayI16RenderObjectDataLj4EEbbbi [DoForwardShaderRenderLoop(undefined dynamic_array<4, bool, bool, bool, int, RenderObjectData?>?&&)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:207529:3
18. __Z12DoRenderLoopR10RenderLoop13RenderingPathR11CullResultsR14ShadowMapCacheb [DoRenderLoop?3(RenderLoop?1?&)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:295728:2
19. __ZN6Camera8DoRenderER11CullResultsPFvRS_R10RenderLoopS1_Ei [Camera::DoRender?_(undefined?F?*&, void, undefined?S?&)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1012903:11
20. __ZN6Camera6RenderER11CullResultsR17ShaderPassContextPK21CameraRenderingParamsi [Camera::Render(int*&&)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:460223:2
21. __ZN6Camera25StandaloneRenderToCubemapEP7TextureiPFvPK9SceneNodePK4AABBR9IndexListPvESA_ [Camera::StandaloneRenderToCubemap(int*, undefined?F?*, void, void*&**)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:356239:7
22. __ZN13ProbeRenderer10RenderCubeEP15ReflectionProbeP13RenderTextureib [ProbeRenderer::RenderCube(int**, bool)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:881872:3
23. __ZN13ProbeRenderer6RenderEP15ReflectionProbeib [ProbeRenderer::Render(int*, bool)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1714306:4
24. __ZN16ReflectionProbes16RenderProbeFacesEP15ReflectionProbei [ReflectionProbes::RenderProbeFaces(int*)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1496532:2
25. __ZN18ReflectionProbeJob3RunEv [ReflectionProbeJob::Run()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1037714:5
26. __ZN16ReflectionProbes40UpdateRealtimeReflectionProbesTimeslicedEv [ReflectionProbes::UpdateRealtimeReflectionProbesTimesliced()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1256179:4
27. __ZN16ReflectionProbes6UpdateEv [ReflectionProbes::Update()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1424141:7
28. __ZN13RenderManager22RenderOffscreenCamerasEv [RenderManager::RenderOffscreenCameras()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:785459:3
29. __Z12PlayerRenderb [PlayerRender(bool)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:935640:2
30. __Z10PlayerLoopbbP10IHookEvent [PlayerLoop(bool, bool, IHookEvent?*)]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:291490:108
31. __ZL8MainLoopv [MainLoop()]@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1497407:3
32. dynCall_v@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:1991723:2
33. Runtime.dynCall@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:277:11
34. Browser_mainLoop_runner/<@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:9345:5
35. Browser.mainLoop.runIter@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:10694:5
36. Browser_mainLoop_runner@blob:null/dd3154a7-2c4b-407c-ac3b-f5a1606d4603:9341:3

there are a lot of messages too in the unity-console after building.

Code (CSharp):

1. Unexpected MonoBehaviour being transferred.
2. UnityEditor.HostView:OnGUI()

 

i opened the same scene again today, and got a error in a DOF script. After deleting those scripts, i got a error like "the namespace unityEngine.UI does not exist". After a new restart of unity it seems to work again. Dabug and Release.

strange, but it is running again.