Ticket #33900: 33900.2.diff

src/wp-includes/functions.php

@@ -4255 +4255 @@
                 return 1;
         }
 
+        $current_site = get_current_site();
+
         if ( defined( 'PRIMARY_NETWORK_ID' ) ) {
                 $main_network_id = PRIMARY_NETWORK_ID;
-        } elseif ( 1 === (int) get_current_site()->id ) {
+        } elseif ( isset( $current_site->id ) && 1 === (int) $current_site->id ) {
                 // If the current network has an ID of 1, assume it is the main network.
                 $main_network_id = 1;
         } else {

src/wp-includes/load.php

@@ -808 +808 @@
 }
 
 /**
+ * Retrieves the current network ID.
+ *
+ * @since 4.6.0
+ *
+ * @global WP_Network $current_site The current network.
+ *
+ * @return int The ID of the current network.
+ */
+function get_current_network_id() {
+        if ( ! is_multisite() ) {
+                return 1;
+        }
+
+        $current_site = get_current_site();
+
+        if ( ! isset( $current_site->id ) ) {
+                return get_main_network_id();
+        }
+
+        return absint( $current_site->id );
+}
+
+/**
  * Attempt an early load of translations.
  *
  * Used for errors encountered during the initial loading process, before