I’d recommend a complete backup just in case then update my PHP as needed. That should normally be all that is necessary.
You might find a theme or plugin that is incompatible within your install. You’ll need to deal with those issues if they arise but the WordPress itself will be compatible.
PHP is not a compiled language if that was what you were thinking.
]]>Call your host for help or look into your htaccess file, your PHP.ini file, and your control panel to see which PHP those think your server is running.
If you have multiple WordPress installs (I’m not talking about multisite specifically) on that server they may each be seeing a different PHP version also.
You need to consider that. Of course the multisite will be running whatever PHP it sees as its assigned version on all its sub-sites.
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