Using Transients to Display Errors

display-transient-errors.php

if ( $errors = get_transient( "my_save_post_errors_{$post_id}_{$user_id}" ) ) {
    foreach( $errors as $error ) { ?>
        <div class="error"><p>
            <?php echo $error; ?>
        </p></div><?php
    }
    delete_transient( "my_save_post_errors_{$post_id}" )
}

save-transient.php

if ( ! empty( $errors ) ) {
    set_transient( "my_save_post_errors_{$post_id}_{$user_id}", $errors, 45 );
}