WordPress at a glance
filter is not described

customize_validate_(setting_id) filter-hook . WP 1.0

This filter is documented in wp-includes/class-wp-customize-setting.php

Usage

add_filter( 'customize_validate_(setting_id)', 'filter_function_name_4389', 10, 3 );
function filter_function_name_4389( $new WP_Error, $unsanitized_value, $setting ){
	// filter...

	return $new WP_Error;
}
$new WP_Error
-
$unsanitized_value
-
$setting
-

Where the hook is called

WP_Customize_Manager::validate_setting_values()
wp-includes/class-wp-customize-manager.php 2286
$late_validity = apply_filters( "customize_validate_{$setting->id}", new WP_Error(), $unsanitized_value, $setting );

Where the hook is used (in WP core)

wp-includes/class-wp-customize-setting.php 185
add_filter( "customize_validate_{$this->id}", $this->validate_callback, 10, 3 );