Site Down after Upgrade to Latest version: 3.11.46

The site has crashed after updating to Latest version: 3.11.46. I have tow (2) installations - I am fearful of upgrading the second installation as the first one is now not accessible.

Is it possible to have a way of down-grading to previous version if current version is experiencing problems? This would help in cases where a bug has manifested and up-time or previous functionality status is a critical service.

With best regards,

Used a snapshot to re-install Software version: 3.11.38 and site is now accessible