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Fixed in 2018.3.X

Fixed in 5.5.X, 5.6.X, 2017.1.X, 2017.2.X, 2018.1.X, 2018.2.X



Found in



Issue ID




Unity throws out Fatal Error: Callback registration failed kMaxCallback



Unity throws out Fatal Error: "Callback registration failed kMaxCallback" after working with the project for 30 minutes or more. It appears randomly.

1. Actively use Unity for more than 30 minutes

Actual: Unity continues to work
Result: Unity crashes with Fatal Error.

Reproducible with: 2017.1.4f1, 2017.2.3p1, 2017.4.4f1, 2018.1.3f1, 2018.2.0b6

Reproduced on macOS, Windows, Linux.
Bug Report window does not appear.
Scene files are not restored after reopening Unity so all not saved Scenes are lost.

  1. karl_jones

    Jan 04, 2019

    Please file a new bug report If you are still encountering this problem. The error message is a symptom and can be caused by many different areas. The area for this bug has been fixed.

Comments (202)

  1. phmello8

    Aug 10, 2018 20:49

    It keeps happening to me, it's not fixed. 2018.2.2f1.
    Just like GIAWA said, it randomly crashes when coming back from editing scripts, for me in MonoDevelop.

  2. jet-pack

    Aug 07, 2018 12:36

    Happens to me every 4-8 hours. 2018.2.0f2, Windows 10.

  3. Canabinoide-Games

    Aug 05, 2018 18:00

    still happens to me on 2018.2.2f1
    approximately 1 out of 10 times i click on play to test my game, the crash comes.

  4. hippocoder

    Aug 04, 2018 12:17

    "Fixed in future release" but it would be really nice to know what fixes it. This is so if we get a bug in future, we can at least immediately test that case as well, to better create repro cases.

  5. Eldrix

    Aug 04, 2018 02:52

    Happened today in Unity 2018.2.2f1 after working in Unity for a couple hours. I luckily just saved my project.

  6. Linkupdated

    Aug 04, 2018 01:15

    Still happens in unity 2018.2.0f2

  7. Broendholt

    Aug 02, 2018 21:33

    After setting to Colors (Color) as public variables and saving the script (MonoBehaviour) The fatal error happened.
    Unity had been open for around 5 hours.

  8. dccatalin

    Aug 02, 2018 19:26

    Happens to me in 2018.2.0f2 (Windows), usually when recompiling scripts after editing in Visual Studio. Using latest Unity extensions for Visual Studio.

  9. DeadHandInteractive

    Aug 02, 2018 19:07

    Happened to me when editing cloth weights in Cloth component

  10. MVRKHQ

    Aug 02, 2018 18:15

    happens to me on 2018.2.0f2

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