rwmb_validation_message_string

This filter changes the message that shows at the top of the form when validation fails.

apply_filters( 'rwmb_validation_message_string', $message );

It has 1 parameter: $message. The default value is "Please correct the errors highlighted below and try again." The plugin escapes the message, so do not use HTML.

Example

add_filter( 'rwmb_validation_message_string', function () {
    return 'Some fields are not correct. Please check the fields in red.';
} );