Plugin Installation Error in Craft 3 / PHP Version I tried to install "Field Manager" Plugin and get following error:

symfony/console v3.4.4 requires php ^5.5.9|&gt;=7.0.8 -&gt; your PHP version (7.2.1) overridden by "config.platform.php" version (7.0) does not satisfy that requirement.

Theres is no config.platform.php anywhere and i have PHP 7.2.1 installed. How can i fix that?

EDIT:
Ok, config.platform.php refers to composer.json entry. I changed it to 7.2 and could install it via command line. Possibly worked via CP too.
Usually when you see that error, Craft was composer install/update'd on one environment with say, PHP 7.2.  Composer then pulls in the highest supported dependencies for that environment.

The composer.lock file is pushed to a different environment with say, PHP 7.1, creating a conflict the next time Composer needs to run.

You can do this to force Composer to use the lowest common denominator for all of your environments: https://github.com/craftcms/craft/blob/master/composer.json#L34-L36