I have a post_type named room_type and a taxonomy room_facility. Between them I want a relationship. Furthermore I would like to add a value for each relationship room_type and room_facility. So the frontend looks like this: [![enter image description here][1]][1] The value is stored in postmeta with a meta_key _room_facility_key_<ID>, where <ID> is the id from room_facility and a post_id from room_type. I think this is the easiest way to link the value to room_type and room_facility, right? [![enter image description here][2]][2] You can see I get the values stored in database. The problem is to save them. Here is my code. To add the metabox: function room_facility_custom_meta() { add_meta_box( 'room_facility_meta', __( 'Meta Box ', 'room_facility-textdomain' ), 'room_facility_meta_callback', 'room_type' ); } add_action( 'add_meta_boxes', 'room_facility_custom_meta' ); My callback function function room_facility_meta_callback( $post ) { //nonce_field wp_nonce_field( basename( __FILE__ ), 'room_facility_nonce' ); $tax = "room_facility"; $term_facilities = get_terms( $tax, array('hide_empty' => false)); $term_checked_facilities= wp_get_post_terms($post->ID, $tax); foreach($term_facilities as $term){ $room_facility_id = $term->term_id; /* the meta_key for postmeta, note there is the room_facility included, * since there should be a relationship between post_id (in this case from taxonomy "room_type") * and "room_facility" */ $meta_key = "_room_facility_key_".$room_facility_id; //value from the postmeta $room_facility_value = get_post_meta($post->ID, $meta_key); ?> <div class="row"> <label for="checkbox_<?php echo $room_facility_id ?>"> <input type="checkbox" name="checkbox_<?php echo $room_facility_id ?>" id="checkbox_<?php echo $room_facility_id ?>" <?php checked( myArrayContainsWord($term_checked_facilities, $term->term_id)); ?> /> <?php _e( $term->name, 'prfx-textdomain' )?> </label> <input type="text" name="text_<?php echo $room_facility_id ?>" id="text_<?php echo $room_facility_id ?>" value="<?php if ( !empty ( $room_facility_value[0] ) ){ echo $room_facility_value[0]; }?>" /> </div> <?php } //end foreach } My save function function room_facility_meta_save( $post_id ) { // Verify this came from the our screen and with proper authorization, // because save_post can be triggered at other times //if ( !wp_verify_nonce( $_POST['room_facility_nonce'], plugin_basename(__FILE__) )) { <-- THIS DIDN'T WORK if(! isset( $_POST['room_facility_nonce'] )){ return $post_id; } // Verify if this is an auto save routine. If it is our form has not been submitted, so we dont want // to do anything if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) return $post_id; //wp_set_object_terms( 742, array(211), 'room_facility'); $taxonomy = "room_facility"; $term_facilities = get_terms( $taxonomy, array('hide_empty' => false)); foreach ($term_facilities as $tax => $term) { $room_facility_id = $term->term_id; /* the meta_key for postmeta, note there is the room_facility included, * since there should be a relationship between post_id (in this case from taxonomy "room_type") * and "room_facility" */ $meta_key = "_room_facility_key_".$room_facility_id; //update postmeta room_facility_key_<ID> if( isset( $_POST[ "text_".$room_facility_id] ) ) { update_post_meta( $post_id, $meta_key, sanitize_text_field( $_POST[ "text_".$room_facility_id] ) ); } //set wp_term_relationships for room_type and room_facility if( isset( $_POST[ 'checkbox_'.$room_facility_id ] ) ) { //wp_set_post_terms( $post_id, $term, $taxonomy); <-- WRONG function $error_obj = wp_set_object_terms( $post_id, (int)$term->term_id , $taxonomy); } /*else { wp_set_post_terms( $post_id, $term, $taxonomy); }*/ } } add_action( 'save_post', 'room_facility_meta_save' ); I'm not sure if the save function is called, because when I do a echo '<script>alert("test")</script>'; Nothing happens... I know I posted a lot of code but I really don't Have an idea why its not working. Feel free to ask if you have a question. [1]: https://i.sstatic.net/5ESQN.png [2]: https://i.sstatic.net/PZ2Nd.png