Ticket #41805: 41805.2.diff

src/wp-admin/includes/schema.php

@@ -905 +905 @@
                 $errors->add( 'empty_sitename', __( 'You must provide a name for your network of sites.' ) );
 
         // Check for network collision.
-        if ( $network_id == $wpdb->get_var( $wpdb->prepare( "SELECT id FROM $wpdb->site WHERE id = %d", $network_id ) ) )
-                $errors->add( 'siteid_exists', __( 'The network already exists.' ) );
+        $network_exists = false;
+        if ( is_multisite() ) {
+                if ( get_network( (int) $network_id ) ) {
+                        $errors->add( 'siteid_exists', __( 'The network already exists.' ) );
+                }
+        } else {
+                if ( $network_id == $wpdb->get_var( $wpdb->prepare( "SELECT id FROM $wpdb->site WHERE id = %d", $network_id ) ) ) {
+                        $errors->add( 'siteid_exists', __( 'The network already exists.' ) );
+                }
+        }
 
         if ( ! is_email( $email ) )
                 $errors->add( 'invalid_email', __( 'You must provide a valid email address.' ) );