Mismatched Magento version while using composer

Question

I currently have Magento running on Ubuntu Xampp, and attempted to run composer on a theme file, which prompted me to install a load of PHP extensions. I did this (7.2 for all of them, same as system version) which fixed those errors, but then it suddenly came up with

magento/framework 100.0.9 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.2.15) does not satisfy that requirement.

This is in response to composer install in the relevant theme folder.

However, the Magento admin panel clearly states that I'm on version 2.3.1 which does support PHP 7.2.11 (which is earlier than 7.2.15, but surely this shouldn't be a breaking change). I installed Magento through the bitnami addon installer to Xampp, which could be the cause as it somehow installed an older version? (Although again, admin panel states I'm running 2.3.1). Could this be something to do with the version the theme in specific is looking for?

Any advice would be very appreciated. Thanks!

Answer 1

If you have a third party extension it could be the reason why you got that error. The solution would be either disable first or uininstall that extension or look for that third party extension's composer.json file and find required PHP version, if your current PHP version is not available in the "require" then please add it.

Do it like below:

"require": {
        "php": "~5.5.0|~5.6.0|~7.0.0|7.2.15"
    },