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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. 29242e3df014554acd69ed6158f73037?d=mm


    Oct 20, 2017 08:42

    Having the same on 5.6.3p4

  2. 6e9f961aa85ab0237a78df633f549358?d=mm


    Oct 20, 2017 08:12

    Having the same on 2017.2.0f3 64bits

  3. 0003948d26e1c9702737e1d8afcced09?d=mm


    Oct 19, 2017 11:23

    I'm having this error on 5.6.3p4. Very annoying!

  4. 79393c2a8082cb2ea4df45050cb8775e?d=mm


    Oct 17, 2017 07:58

    Noticed : 2017.2.0f3

  5. 083d9b81644907fc07953e699cb77036?d=mm


    Oct 13, 2017 10:47

    Same here on 2017.2.0f3 64bits. The issue drove me nuts until I found this report.

  6. 9c5e2c5ea480b256ffa813b2874f82d7?d=mm


    Oct 13, 2017 07:55

    I've also been encountering this assert message from 2017.1.0p3

  7. 8de74d5d2f6f84c4e86c44d1ab101382?d=mm


    Oct 09, 2017 09:37

    Also encountering this error:
    Assertion failed: Assertion failed on expression: 'Thread::CurrentThreadIsMainThread()

  8. 9bb6a7daa128730c59ea4a8d87ffddb7?d=mm


    Oct 09, 2017 01:00

    async Fbx with anim from assetbundle,get the error:
    Assertion failed: Assertion failed on expression: 'Thread::CurrentThreadIsMainThread()'

  9. 14b4b1a75a5f1cac048fd3082ed9ea62?d=mm


    Oct 04, 2017 16:00

    If you remove the Animator, and just reference parts of the Animator in a script like the Animation Controller and Avatar... you will still receive these errors.

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