Known issues in Unity versions and packages
Some versions of Unity or Unity plugins have known incompatibilities blocking apps from working as expected on HoloLens 2 or Windows Mixed Reality devices. While we generally support all LTS versions of Unity and their verified plugins, we recommend avoiding those specific builds of Unity and Unity plugins to ensure your apps work as expected.
The latest Unity 2021 release has a known blocking performance bug with HoloLens 2 if the project is using URP rendering pipeline.
For new projects using URP rendering, we recommend using latest Unity 2020.3.35f1 or later LTS with the latest Mixed Reality OpenXR plugin to avoid this issue.
If using other Unity releases, consult the known active blocking issues to ensure you avoid builds with other blocking issues.
Active blocking issues
|Blocking issues||Status & Last Update||Versions with issue||Mitigation|
|ARM32 UWP Unity apps built in release mode using Visual Studio 2022 will hit an internal compiler error in Visual Studio.||Pending release:
|Visual Studio 2022
|Use Visual Studio 2019 or 2022 version <= 17.0|
|HL2 app using URP, WindowsXR plugin and Gamma color space rendering has worse render performance in Unity 2020 or later.||Investigating:
with URP 10.*.*
and Windows XR Plugin 4.*.*
|Upgrade to OpenXR Plugin instead of WindowsXR plugin|
|HL2 app using URP has worse render performance in Unity 2021 compared to Unity 2020.||Investigating:
with URP 12.*.*
|Either avoid URP in Unity 2021 or use URP in Unity 2020.LTS|
Resolved blocking issues
|Blocking issues||Status & Last Update||Versions with issue||Versions with fixes|
|HL2 app using Unity's Burst package (e.g. commonly used when using URP) will hit ILCPP compile error in VisualStudio.||Fixed:
|Unity Burst package
1.6.5 or 1.7.0~1
|Use Unity Burst package 1.6.6 or 1.7.2 or later versions.|
|Application with default splash screen will show four spinning dots when launching on HL2, or after the application is suspended and resumed.||Fixed:
|Unity 2020.3.32-34f1 and Unity 2021.2.17~19f1 and Unity 2021.3.0~3f1||Use Unity 2020.3.35f1 or Unity 2021.3.4f1 or later|
|HL2 application shows severely jittery image.||Fixed:
|Unity 2020.3.21f1 to
|Use Unity 2020.3.24f1
|OpenXR backend with URP can deadlock on HL2.||Fixed:
|Unity 2020.3.0f1 to
|Use Unity 2020.3.8f1
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