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Fixed in 2020.2.X

Fixed in 2019.3.X, 2020.1.X

Votes

8

Found in

2019.3.0b4

2019.3.0f6

2020.1

2020.2

Issue ID

1219335

Regression

Yes

[macOS] "DllNotFoundException: libMonoPosixHelper.dylib" error is thrown in Build when using System.IO.Compression.DeflateStream

MacOS

-

How to reproduce:
1. Open the attached project
2. Go to the Build Settings (File->Build Settings)
3. Enable the Development Build option
4. Press the "Build And Run" button
5. In Build, observe the Console Window

Expected result: No errors are thrown
Actual result: "DllNotFoundException" error is thrown

Reproducible with: 2019.3.0b4, 2019.3.3f1, 2020.1.0a25, 2020.2.0a1
Not reproducible with: 2017.4.37f1, 2018.4.18f1, 2019.3.0b3

Note: Error isn't thrown on Windows

  1. Resolution Note (fix version 2020.2):

    Fixed in Unity 2020.2.0a8

  2. Resolution Note (fix version 2020.1):

    Fixed in Unity 2020.1.0b8

  3. Resolution Note (fix version 2019.3):

    Fixed in Unity 2019.3.14f1

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Comments (3)

  1. jesusluvsyooh

    Aug 15, 2025 18:34

    This issue is back, libMonoPosixHelper.dylib is included, but the codes looking for it in wrong location. (regarding using System.IO.Compression; and DeflateStream)

    Root/libMonoPosixHelper.dylib (included, but says cannot be found)
    Root/Data/Managed/libMonoPosixHelper.dylib (copy it here, now it can be found)

    Dedicated Server build, happens on Unity 2022, and 6000.

  2. alesrazym

    Mar 16, 2020 06:13

    Have the same issue in 2019.3.5f1

  3. german_g

    Mar 13, 2020 21:43

    "Development build" option is not necessary to reproduce.

    Selecting compression methods other then default - doesn't solve the issue.

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