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filter is not described

enable_maintenance_mode filter-hook . WP 4.6.0

Filters whether to enable maintenance mode.

This filter runs before it can be used by plugins. It is designed for non-web runtimes. If this filter returns true, maintenance mode will be active and the request will end. If false, the request will be allowed to continue processing even if maintenance mode should be active.

Usage

add_filter( 'enable_maintenance_mode', 'filter_function_name_1627', 10, 2 );
function filter_function_name_1627( $enable_checks, $upgrading ){
	// filter...

	return $enable_checks;
}
$enable_checks(true/false)
Whether to enable maintenance mode.
Default: true
$upgrading(int)
The timestamp set in the .maintenance file.

Where the hook is called

wp_maintenance()
enable_maintenance_mode
wp-includes/load.php 208
if ( ! apply_filters( 'enable_maintenance_mode', true, $upgrading ) ) {

Where the hook is used (in WP core)

Does not used.