Search Issue Tracker

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. hippocoder

    Aug 23, 2018 13:13

    Tried the latest 2018.2.5f1 which claims to fix the issue, however unity crashed and quietly closed with no error at all this time. It never did so like this in previous versions so it could be related or simply a bad fix.

  2. ChiliGuaya

    Aug 23, 2018 05:40

    Happened today to me 5 times .-. v2019.2.3f1

  3. hippocoder

    Aug 22, 2018 21:26

    (1056461) - Editor: Fixed case of "Callback registration failed kMaxCallback" error.

    Feel free to test.

  4. Le_Vailus

    Aug 22, 2018 09:25

    Happens at least once a day, in latest versions of Unity, its been like a month, hope this gets resolved soon.

  5. Fr33zerPop

    Aug 21, 2018 22:42

    This is not resolved. Please make a new listing. I'm having this issue in 2018.2.3f1.
    The last time it happened I had just saved in the last 10 seconds. Is there a relationship to actually saving?

  6. WeltallZero

    Aug 21, 2018 17:08

    Happens on latest Unity version (2018.2.3f1). Happens very often (once a day), and everything not saved is lost. Unity also doesn't prompt to send a report (might have been removed from current versions of Unity).

    As an aside, it's really bad form to forbid users from voting on an issue that is "solved in a future version", when the issue has been happening since Unity 5 at least and still happens.

  7. OriginalMonkeybot

    Aug 21, 2018 12:12

    It is seemingly random,And is still happening frequently(>5 times a day)


  8. metroidsnes

    Aug 19, 2018 08:22

    It happenes at least once a day, Unity 2018.2.2f1, Windows 10. Last line in callstack is `UnityEditor.Handles:DrawLine(Vector3, Vector3)`. This method was called by my code from OnGUI().

  9. hjonersjr

    Aug 16, 2018 17:11

    "Voting Disabled for Resolved Issues (Fixed)"

    This, most certainly, is not resolved. Just like everyone else here, it keeps happening randomly after I save a script and come back into the Unity Editor. Fortunately I've gotten in the habit of saving my scene after every single change.

  10. nobelxer

    Aug 12, 2018 13:32

    same here, keep crashing at random moments after saving a script in VS2017...

Add comment

Log in to post comment

All about bugs

View bugs we have successfully reproduced, and vote for the bugs you want to see fixed most urgently.