Fixes Gravity Forms Custom Validation Message

gf-custom-validation.php

<?php

add_filter( 'gform_field_validation', 'mytheme_fix_custom_validation', 10, 4 );

/**
 * Fixes Gravity Forms Custom validation message.
 * 
 * @link https://docs.gravityforms.com/gform_field_validation/
 *
 * @param array  $result  The result array.
 * @param string $value   The value of the field.
 * @param array  $form    The Gravity Form array.
 * @param object $field   The form field object.
 *
 * @return array  The result array.
 */
function mytheme_fix_custom_validation( $result, $value, $form, $field ) {
	if ( ! $result['is_valid'] && ! empty( $field->errorMessage ) ) {
		$result['message'] = $field->errorMessage;
	}
	return $result;
}