On creating a new unity project or upgrading any project in 2021.2a10 resulting "Opening file failed" popup appears which states that the extentions.dll file does not have permissions.
Refer attached video.

Steps to Repro:
1. Download Unity Editor version 2021.2a10 through 'Download Assistant'.
2. HUB > Installs > Locate > 2021.2a10
3. Projects > New > Select Unity Version 2021.2a10
4. Create a New Unity Project or upgrade any project.

Actual result:
'Opening file failed' popup appears on creating/upgrading any project when the editor is installed via DA.

Expected result:
When the editor is installed through DA then on creating/upgrading Projects they should get created and Upgraded gracefully.

Reproducible in:
2021.2.0a10.

Working Fine in:
2021.2.0a9, 2021.1.0f1, 2020.3.2f1.

Environment:
Only on macOS

Workaround:
When the permissions for the extentions.dll file are given manually then the project is created or upgraded gracefully.

Note:
1] On clicking the 'Force Quit' option editor crashed with a fatal error
the crash log is attached for reference.
2] When the editor is installed through HUB then on creating/upgrading Projects they get created and Upgraded gracefully.
3] Unity Hub installed Version 2.4.3 (2.4.3)