I don't understand wordpress, why is this wp_get_environment_type function undefined?

Isn't this a "native" wordpress function? How can I make it defined? Here is my code inside of a MU-Plugin file:

add_action('admin_init', function() {
$environment = wp_get_environment_type();
//...

I don't understand wordpress, why is this wp_get_environment_type function undefined?

Isn't this a "native" wordpress function? How can I make it defined? Here is my code inside of a MU-Plugin file:

add_action('admin_init', function() {
$environment = wp_get_environment_type();
//...

• plugins
• mu-plugins

1 Answer 1

It is a core WP function, but only after WordPress version 5.5.0.

If you're using an older version of WordPress, it won't exist yet.

Do this:

add_action('admin_init', function() {
if ( ! function_exists( 'wp_get_environment_type' ) ) {
    return;
}
$environment = wp_get_environment_type();
//...

Or, better still, make sure your WordPress installation is up to date.