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Unity Editor becomes unusable after downgrading UI Toolkit Package Version

UI Toolkit


How to reproduce:
1. Download and open project '' from Google Drive
2. Open Package Manager
3. Find UI Toolkit in Package Manager
4. Update UI Toolkit to '1.1.0-preview.3' version
5. Observe

Reproducible with: 2020.2.0b9, 2020.2.0b11, 2021.1.0a2 2021.1.0a3, 2021.1.0a6
Not reproducible with: 2020.1.14f1, 2020.2.0a1, 2020.2.0b5, 2020.2.0b6, 2020.2.0b8, 2021.1.0a1
Couldn't test with: 2018.4.0f1, 2018.4.29f1, 2019.4.0f1 (Couldn't downgrade the project)

Notes: <2020.2.b11 Editor UI becomes unusable and broken also on entering Play Mode crash occurs. On 2021.1.0a2 and above Package Manager, Asset Store, Toolbar gets removed and after a restart, a black screen appears. Tests were also done on Windows, results are the same.

  1. Response avatar

    Resolution Note:

    UIToolkit is a preview package and has no stable version. As UIToolkit has functionality in the Game as well as Editor, downgrading unstable package could cause issues with Editor.

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