Old website or shop broke after a PHP version change
The site "broke" on its own, you can't log into the admin, and the same copy works elsewhere? The most common cause: your host retired an old PHP version and moved the site to a newer one. All hosts do this eventually, because old versions no longer get security fixes. Old code stops working with new PHP.
What to check
- The PHP version in your hosting control panel. If you have a working copy elsewhere, compare the versions.
- The error log in the hosting panel. It usually says exactly which file and line the site fails on.
- Changed files over FTP: if core files changed without you touching them, it may be a hack rather than PHP.
Quick fix
If the host still allows it, switch to the oldest available PHP version. The site often comes back right away.
Lasting fix
An old PHP version only buys time; the host will remove it eventually. With WordPress, updating core, plugins and theme and replacing abandoned plugins is usually enough. An old custom-built shop needs its code updated for new PHP, or a move to a new system.