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Fixed in 2018.1

Fixed in 5.6, 2017.1, 2017.2, 2017.3



Found in


Issue ID




Loading an asset that has an Animator component from an Asset Bundle with LoadAsync throws "Assertion failed" error

Asset Bundles


The project provided uses "Asset Bundle Browser" tool but it has anything to do with the bug

To reproduce:
1) Open the attached project "943438repro"
2) From the menu open Windows -> Asset Bundle Browser
3) Press "Build" to build the Asset Bundle
4) Open "AssetBundleTest.unity" scene
5) Enter play mode
6) On the GUI in the top right corner press "Load Bundle (Async)"
Result: "Assertion failed: Assertion failed on expression: 'Thread::CurrentThreadIsMainThread()" Error is thrown

Note: this can be reproduced without the "Asset Bundle Browser" tool
When using the "Asset Bundle Browser" tool and the script for loading the asset in the project some minor tweaking might be required depending on the platform it is being tested on

Reproducible on both Mac and Windows

Reproduced on: 2017.3.0a5, 2017.2.0b8
Regression introduced with: 2017.2.0b6
Not reproducible on: 2017.2.0b5 and earlier


Comments (19)

  1. 44b5eb94f6fbf03376bc493289f7f18d?d=mm


    Jan 17, 2018 20:14

    Having the same issue on 2017.2.0f3

  2. 288b67e0334a582a2895c6c11f53f802?d=mm


    Dec 14, 2017 00:01

    Having the same on 2017.2.0f3 64bits

  3. 87e02a7335f92a1c59339927df25fa97?d=mm


    Dec 07, 2017 10:16

    Would it be possible to merge the fix into 2017.1 ? I'm still seeing this issue in 2017.1.2p3. Thanks

  4. De42bbded6bc05bcd5cc3782d6016c78?d=mm


    Nov 07, 2017 13:08

    Its fixed in version 2017.3.0b8.
    "Animation: Fixed Asserts when loading AssetBundle with AnimationClip asynchronously (943438)"

  5. 87e02a7335f92a1c59339927df25fa97?d=mm


    Nov 07, 2017 08:20

    Any idea in what future release this issue will be fixed?

  6. 8aadef87bee3a81b6e1555b605584d43?d=mm


    Nov 04, 2017 03:30

    Why is this marked as resolved? This is still an issue in 2017.2...

  7. Cfbe34c57475c74177cb04975e950ccf?d=mm


    Oct 31, 2017 10:42

    Seeing a lot of this error when using bundles in the editor with 2017.0.1p4 or 2017.1.1.f1 (haven't tried anything newer yet)

  8. 0ae7031ed9df59637ccefdaabc4f1ab0?d=mm


    Oct 30, 2017 07:48

    Has this issue in 5.6.4p1

    Assertion failed on expression: 'Thread::CurrentThreadIsMainThread()'
    0x00000001417C3E1B (Unity) StackWalker::GetCurrentCallstack
    0x00000001417C5AFF (Unity) StackWalker::ShowCallstack
    0x000000014179FDC0 (Unity) GetStacktrace
    0x0000000140D4B13B (Unity) DebugStringToFile
    0x0000000140D4B91C (Unity) DebugStringToFile
    0x000000014083A80F (Unity) AnimationClip::BuildMecanimDataMainThread
    0x000000014083C3C3 (Unity) AnimationClip::Transfer<StreamedBinaryRead<0> >
    0x000000014084801B (Unity) AnimationClip::VirtualRedirectTransfer
    0x00000001414CF29E (Unity) SerializedFile::ReadObject
    0x000000014108EF7F (Unity) PersistentManager::ReadAndActivateObjectThreaded
    0x00000001410914E4 (Unity) PersistentManager::LoadFileCompletelyThreaded
    0x000000014102AB75 (Unity) LoadSceneOperation::Perform
    0x000000014102A290 (Unity) PreloadManager::ProcessSingleOperation
    0x000000014102A3FD (Unity) PreloadManager::Run
    0x000000014102AF47 (Unity) PreloadManager::Run
    0x00000001411D685C (Unity) Thread::RunThreadWrapper
    0x00007FF8BE3F2774 (KERNEL32) BaseThreadInitThunk
    0x00007FF8C00E0D51 (ntdll) RtlUserThreadStart

  9. C1727db7d98b960ede5c3e38e4f3bb8a?d=mm


    Oct 25, 2017 18:21

    I had this error "Assertion failed: Assertion failed on expression: 'Thread::CurrentThreadIsMainThread()'
    " when loading a prefab from an asset bundle in version 2017.1.1f1.

  10. 51a4ea5ae43053d00dd7c5416c6b2ce7?d=mm


    Oct 24, 2017 07:57

    asserted 2017.2f3

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