I have a strange issue. The custom rewrite rules are registered correctly in my plugin activation hook. But, if I go to the permalinks settings page and clic on "Save changes" I lost the rewrite rules registered by my plugin. I have to deactivate and reactivate my plugin to get the custom rewrite rules back again.

Here my activation and deactivation hook

register_activation_hook( __FILE__ , 'properties_plugin_activation' );
function properties_plugin_activation(){
    //add custom rewrite rules and custom vars before flush_rewrite_rules()

register_deactivation_hook( __FILE__ , 'properties_plugin_deactivation' );
function properties_plugin_deactivation(){

Here my rewrite rules:

// Register a new vars to be used in the rewrite rules
function properties_add_query_vars( $vars) {
  $vars[] = "action"; // name of the var as seen in the URL
  return $vars;
add_filter('query_vars', 'properties_add_query_vars');

// Add the new rewrite rules
function properties_add_rewrite_rules() {
    add_rewrite_rule( 'properties/search/?$' , 'index.php?post_type=properties&action=search' , 'top' );
    $config = new PConfig();
    foreach($config->taxonomies as $taxonomy){
        add_rewrite_rule( 'properties/'.$taxonomy["slug"].'/(.+)/?$' , 'index.php?post_type=properties&'.$taxonomy["slug"].'=$matches[1]' , 'top' );

1 Answer 1


properties_add_rewrite_rules should be hooked to init so it runs on every request.

Rules can be flushed at any time- loading the permalinks settings page calls flush_rewrite_rules, and your rules weren't added on that request, so they disappear.

  • That makes sense but I've read in a lot of sites that the add_rewrite_rules should be called only in activation/deactivation hooks because of possible performance issues of running add_rewrite_rules in every page request. What do you think?
    – cybmeta
    Commented Sep 2, 2013 at 23:39
  • 2
    adding them on every request is fine, it's flushing that shouldn't be done on every request- only activation and deactivation. that's the expensive operation.
    – Milo
    Commented Sep 3, 2013 at 0:17

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