Startup error after installation - Unable to initialize module Module

Trying out Kirby3 for the first time. Unzipped into a subdomain and used AddHandler to force use of php 7.1. Getting this message at startup.

Whoops\Exception\ErrorException thrown with message "PHP Startup: SourceGuardian: Unable to initialize module
Module compiled with module API=20100525
PHP compiled with module API=20160303
These options need to match

#0 Whoops\Exception\ErrorException in Unknown:0

No idea what is wrong.

Hm, I’ve never seen this error message before. A short search uncovered this SO thread:

I take it you are on a remote server. Is that your hoster’s recommended way to change the PHP version?

It is a remote server. I’ve used that approach before in testing with other stuff and it works. I just went back in using cpanel and set it to 7.1 for the subdomain folder and now it works. Lesson learned. Thanks.