Unity Integration: UnauthorizedAccessException and Broken IntelliSense in Rider

Problem

IntelliSense fails to work in Rider after encountering the following error upon switching to Unity:

UnauthorizedAccessException: Access to the path "C:\\Program Files\\JetBrains\\JetBrains Rider 2023.2.2\\product-info.json" is denied.

Restarting Rider temporarily resolves the issue, but the error recurs frequently.

Cause

This issue occurred due to an outdated Rider version.

Resolution

1. Update JetBrains Toolbox:

   • Launch JetBrains Toolbox to ensure it is functional and up-to-date.
   • If Toolbox is not opening, try reinstalling or troubleshooting Toolbox first.

2. Update to the Latest Rider Version:

   • Open JetBrains Toolbox.
   • Check for updates and install the latest version of Rider.

3. Uninstall Outdated Versions:

   • Navigate to Control Panel \ Programs \ Programs and Features and remove any outdated Rider installations to avoid confusion.

4. Set JetBrains Toolbox to Start on Startup (Optional):

   • Open JetBrains Toolbox.
   • Go to Settings (gear icon) and enable "Start at Login" or similar startup options to ensure it runs automatically at system startup.

By following these steps, the recurring UnauthorizedAccessException and IntelliSense failure should no longer occur.