After update to core 9.2 end up PHP Fatal error: Trait 'Symfony\Bridge\PhpUnit\Legacy\PolyfillAssertTrait'

Thanks a lot for your comment, Raineri. I was also able to solve my problem just by installing the package

I had the same problem while using Upgrade Status and didn't realize thats where it came from until I saw the 2 above comments. I installed the same package and problem is fixed.

Had the same issue. #8 solved it. Thanks.

Had the same issue. #8 solved it. Thanks.

Same problem, when using Upgrade Status module. package from #8 solved it. Thanks

The solution #8 worked fine for me in Drupal 9.x version to running the Unit test.