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action is not described

wp_validate_site_data action-hook . WP 5.1.0

Fires when data should be validated for a site prior to inserting or updating in the database.

Plugins should amend the $errors object via its WP_Error::add() method.

Usage

add_action( 'wp_validate_site_data', 'action_function_name_2729', 10, 3 );
function action_function_name_2729( $errors, $data, $old_site ){
	// action...
}
$errors(WP_Error)
Error object to add validation errors to.
$data(array)
Associative array of complete site data. See {@see wp_insert_site()} for the included data.
$old_site(WP_Site/null)
The old site object if the data belongs to a site being updated, or null if it is a new site being inserted.

Where the hook is called

wp_prepare_site_data()
wp_validate_site_data
wp-includes/ms-site.php 499
do_action( 'wp_validate_site_data', $errors, $data, $old_site );

Where the hook is used (in WP core)

wp-includes/ms-default-filters.php 43
add_action( 'wp_validate_site_data', 'wp_validate_site_data', 10, 3 );