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.

Changing the PHP version caused incompatibility with themes, plugins, or code; update dependencies, fix errors, or revert to the previous PHP version.

Changing the PHP version can break a website if the theme, plugins, or custom code are not compatible with the new PHP release. Before upgrading, always take a full backup and test the site on a staging environment first.

First check the error

Enable error logs or check your hosting's error log. Common messages include:

"Fatal error"
"Deprecated function"
"Call to undefined function"
"Parse error"
"IonCube Loader not installed"
Quick recovery
Log in to your hosting control panel.
Switch PHP back to the previous version that was working.
Confirm the site comes back online.
Then identify compatibility

Tell me:

What platform is the site built on? (WordPress, Laravel, custom PHP, Magento, etc.)
What PHP version did you change from and to?
What exact error message do you see?
Which hosting provider are you using?

If your actual goal is still to choose a business/profession code (GST/NIC/Udyam/etc.), please describe the business activity in plain language and I'll help identify the most appropriate code.