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Found in [Package]


Issue ID




"Unable to find internal function `System.Buffer::InternalMemcpy`" error is thrown when entering Play Mode

Package: Burst


How to reproduce:
1. Open the attached project “IN_14611”
2. Open the SampleScene in Scenes
3. Enter Play Mode
4. Observe the Console

Expected result: the error does not occur upon entering Play Mode
Actual result: the error appears when entering Play Mode for the first time after the BurstCache was created

Reproducible with: 1.7.3 (2021.3.4f1, 2021.3.10f1)
Not reproducible with: 1.7.3 (2020.3.39f1)
Couldn’t test with: 1.7.3 (2021.3.3f1, 2022.1.16f1, 2022.2.0b5, 2023.1.0a10 (due to compiler errors))

Reproducible on Windows 10 Pro

- After deleting Burst Cache in ProjectRoot → Library issue appears again
- Not reproducible in Player

  1. Resolution Note:

    The problem is the calls to Marshal.ReadInt16() and Marshal.ReadInt32() inside the TestSystem.CopyDataFormat1 method. In some versions of Unity, those two calls end up calling System.Buffer.InternalMemcpy, which is unavailable to Burst. The fix is to replace Marshal.ReadInt16() and Marshal.ReadInt32() with custom implementations of those two methods.

    The error message "unable to find internal function..." is admittedly unhelpful, since it doesn't point to the code that caused the problem and thus isn't actionable. We have this in our backlog as something we want to improve.

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