You can choose which version of PHP your account runs, and change it yourself at any time, in cPanel under Select PHP Version.
Which version should I use?
As a rule, the newest version your software supports. Newer releases are faster and receive security fixes; older ones eventually stop being maintained altogether. Your software's own documentation will state the versions it supports – check there first rather than guessing.
What can break
Moving up a major version can stop older code working. The usual symptoms are a blank white page, or a 500 error, immediately after the change. If that happens, switch back to the previous version and the site will return – nothing is lost by trying.
Extensions move with the version
This is the part that catches people out. Each PHP version has its own list of enabled extensions, and they are not copied across when you switch. A site that worked on the old version can fail on the new one purely because an extension it needs is not ticked, even though it was ticked before.
On the same Select PHP Version screen, click through to the extensions list and compare it with the version you came from. Commonly needed ones include mbstring, gd, zip, curl, intl and the database extensions.
Before you change
Take a backup, and change it at a quiet time rather than in the middle of a working day. If you are unsure, open a ticket and we will advise on the right version for your site.
