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Fixed in 2021.2.X

Fixed in 2018.4.X, 2019.4.X, 2020.3.X, 2021.1.X



Found in



Issue ID




"Assertion failed on expression: 'pred(*previous, *i)' " is thrown on additively adding a new scene to a baked scene

Progressive Lightmapper


Assertion failed on expression: 'pred(*previous, *i)' is thrown when a new scene is added additively to an existing baked scene having the "Auto-generate" checkbox off in Lighting settings. Refer the attached video

Steps to reproduce:
1) Download the attached project and open `s1Blue` scene
2) Check "Auto-generate" checkbox ON in Lighting settings and let the scene's lighting auto-bake
3) Uncheck the "Auto-Generate" checkbox in the Lighting window
4) Drag the 's1Red' scene from the Project folder to the Hierarchy to additively load it

Actual result: Assertion failed on expression: 'pred(*previous, *i)' is thrown when a scene is added additively to an existing baked scene

Expected result: No errors are thrown when a scene is added additively

Occurring on: 2019.3.0f6 (69ba09c9b97e), 2019.3.0f3

Working fine on: 2020.1.0a19, 2020.1.0a1, 2019.3.0f2

Environment: Only on Windows

Stack trace: Assertion failed on expression: 'pred(*previous, *i)'
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

  1. Response avatar

    Resolution Note (fix version 2021.1):

    Verified fix in,

    Version: 2021.1.0b12.2144
    Revision: 2021.1/staging 7b84efee645b
    Built: Thu, 11 Mar 2021 10:21:39 GMT

  2. Response avatar

    Resolution Note (fix version 2019.4):

    Verified fix in,

    Version 2019.4.22f1 (9fdda2fe27ad)
    Wed, 03 Mar 2021 01:24:36 GMT
    Branch: 2019.4/staging

Comments (7)

  1. E1d861ff15540a3ac132f917bf78e860?d=mm


    Feb 04, 2021 22:17

    Can confirm! Please fix!

  2. 06ef20d43f209ad25c5bd3df0181d962?d=mm


    Oct 16, 2020 13:34

    Happening on windows Unity 2019.4.12f1 (LTS)
    We loading multiplee scenes and get same amount of errors, kinda annoying and dunno if it affects build performance for leaks?

  3. 592aaf2e46f9d2300bc6787df72f6f2a?d=mm


    Aug 25, 2020 19:56

    Happening on windows Unity 2019.4.8f1 (LTS)

  4. Bd76611a559f170541dfdedfde8c2cbe?d=mm


    Jul 07, 2020 17:57

    Same issue. I am having the same error Messages in Unity 2019.4.0f1 on Windows.

  5. 2f7e3534d5b72db1fd23c78ef7e86375?d=mm


    May 02, 2020 00:56

    For context, here is my stack trace for this same error, from the editor log:

    Assertion failed on expression: 'pred(*previous, *i)'
    (Filename: ./Runtime/Utilities/remove_duplicates.h Line: 77)

  6. F4a7a2f9cc04d71b9612c8bd515405c3?d=mm


    May 01, 2020 19:28

    Happening on Mac as well.

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