How to reproduce:
1. Create and open a new project
2. Create and open a new MonoBehaviour script in Visual Studio
3. Open Preferences window, in the menu bar: Edit > Preferences…
4. Select the External tools tab, toggle on Built-in packages option
5. Click the Regenerate project files button
6. Enter Play mode or reimport assets from Project tabs contextual menu
7. Observe the Console and Visual Studio IDE
Actual result: “IOException” error is thrown and IDE is no longer linked with the project
Expected result: No error is thrown, IDE continues to work as usual
Reproducible with: 2.0.26 (6000.6.0a5), 2.0.27 (6000.6.0a5)
Not reproducible with: 2.0.26 (6000.6.0a4, 6000.0a6), 2.0.27 (6000.0.76f1, 6000.3.16f1, 6000.4.9f1, 6000.5.0b10, 6000.6.0a4, 6000.6.0a6)
Fixed in: 2.0.27 (6000.6.0a6)
Reproducible on: Windows 11
Not reproducible on: No other environments tested
Notes:
- Reproducible while Visual Studio IDE is open
- Reproduced using Visual Studio 2026 and 2022 versions: 18.6.11819 and 17.14.36221 respectively
- Error thrown: “IOException: Sharing violation on path C:\Projects[PROJECT_NAME]\Library\ImmutablePackage.ruleset”