Ticket #56952: 56952.diff

src/wp-includes/class-wp-user-query.php

@@ -840 +840 @@
                                 $result->id = $result->ID;
                         }
                 } elseif ( 'all_with_meta' === $qv['fields'] || 'all' === $qv['fields'] ) {
-                        cache_users( $this->results );
+
+                        // Pluggable.php might not be loaded when this code is executed.
+                        if ( function_exists( 'cache_users' ) ) {
+                                cache_users( $this->results );
+                        }
 
                         $r = array();
                         foreach ( $this->results as $userid ) {