Your site likely broke due to PHP compatibility issues with your code, theme, or plugins. Restore the previous working PHP version, check error logs, and update code/plugins for compatibility.

Changing the PHP version can break compatibility with your site's code, themes, or plugins, causing errors or crashes. Roll back the version, update extensions, enable error logs, and test on staging before switching again.

Reverting to the previous PHP version or updating incompatible files usually restores the normal functionality of the website after changing the PHP version.