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Postponed means that the issue was either a feature request or something that requires major refactoring on our side. Since that makes the issue not actionable in the close future we choose to close it as Postponed and add it on our internal roadmaps and technical debt pages instead.




Found in



Issue ID




[SerializedField] fields produce "Field is never assigned to..." warning



1. Open the attached project (
2. Observe the warning in the console

Expected: field with SerializeField attribute do not produce the warning

Reproduced in 2018.3.0a1, 2018.3.0b1, 2018.3.0b2, 2019.1.0a1
Did not reproduce in 2018.2.8f1
Regression introduced in 2018.3.0a1

  1. Response avatar


    Nov 06, 2019

    #pragma warning disable 0649
    // your code
    #pragma warning restore 0649

    Or disable it globally by adding a file named csc.rsp to the root of you Assets folder, e.g. Assets/csc.rsp, with the following contents without quotes.


    This will tell the C# compiler to not emit a warning for CS0649 / unused fields.

    If you have .asmdefs with csc.rsp in your project, then you also need to add the "/nowarn:0649" line to those csc.rsp files.

  1. Response avatar

    Resolution Note (fix version ):

    This can be fixed using DiagnosticSuppressor API in Roslyn. However, this requires that Unity updates Roslyn to a newer version that supports DiagnosticSuppressor and that proper support for using Roslyn analyzers is added to Unity. The fix of this issue is therefore postponed.

    The new C# compiler is correct in reporting the additional warnings.

    You can disable the warnings with pragmas:

    #pragma warning disable 0649
    // your code
    #pragma warning restore 0649

    Or disable it globally by adding a csc.rsp file to your project and adding command line switch to disable the warning.

Comments (61)

  1. 7d7224d5ef39fd679f9efed50c5912de?d=mm


    Oct 09, 2019 07:43

    You guys only have 100 warnings? I have about 340 of these because I use a lot of serialized attributes over about 200 .cs files. I'm not going to go through 200 scripts and add pragmas to them...

    Setting default Values is NOT a solution because I have had multiple instances where somehow a default value overrode the value I set in the inspector, and I had to go remove the default values from 100 objects to prevent values I specifically set from disappearing!!!

    I'm not sure when it happens (maybe I clicked revert accidentally or something), but whatever the case it causes hours of headaches when it does occur and there is literally NO warning telling you that a bunch of serialized attributes you set on a hundred objects are about to be reset to defaults and override your values.

  2. D376d891ab442d46b58f26d407ccd162?d=mm


    Oct 08, 2019 13:44

    Is there any chance to reopen this? really annoying bug

  3. 51623c5ba2d7468394521762e2cc7009?d=mm


    Oct 08, 2019 04:30

    Using Unity's own preview Standard Assets Controller, I get 120+ issues in my console because of this. Surely there has to be a better solution than just saying "by design"?

  4. 3e64d071a0d538d0b88040e4bfa22d2d?d=mm


    Oct 06, 2019 22:34

    Agreed that this should be re-investigated.

  5. E295481e81a54f69223bd408552c5a1e?d=mm


    Sep 26, 2019 16:33

    This is blatantly NOT intended functionality and the proposed solutions are just workarounds for a bug that should not have been marked resolved.

  6. E7450742b0fb9c4c69426524978c3043?d=mm


    Sep 23, 2019 19:58

    Damn this is bugging!

  7. 5fa445a7e382ed309aab2097ea215163?d=mm


    Sep 23, 2019 14:18

    Please reopen, its really annoying

  8. F25db945e005add93f29ca8e53869f17?d=mm


    Sep 21, 2019 20:52

    This needs a solution. You can't just say "By design" without an actual alternative solution.
    If this is by design then fire your designers and find better ones.

  9. 55d14f6d8457d63f7573846de069a09b?d=mm


    Sep 20, 2019 10:26

    Reopen this, please...

  10. 29b7224f3299d49bbc1741626aaeab16?d=mm


    Sep 18, 2019 11:47

    +1 for reopen....

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