diff --git a/wp-includes/option.php b/wp-includes/option.php
index f52b7efee7..a80de70784 100644
--- a/wp-includes/option.php
+++ b/wp-includes/option.php
@@ -1247,7 +1247,7 @@ function get_network_option( $network_id, $option, $default = false ) {
 	$notoptions_key = "$network_id:notoptions";
 	$notoptions     = wp_cache_get( $notoptions_key, 'site-options' );
 
-	if ( isset( $notoptions[ $option ] ) ) {
+	if ( is_array( $notoptions ) && isset( $notoptions[ $option ] ) ) {
 
 		/**
 		 * Filters a specific default network option.
@@ -1295,6 +1295,11 @@ function get_network_option( $network_id, $option, $default = false ) {
 		}
 	}
 
+	if ( ! is_array( $notoptions ) ) {
+		$notoptions = array();
+		wp_cache_set( $notoptions_key, $notoptions, 'site-options' );
+	}
+
 	/**
 	 * Filters the value of an existing network option.
 	 *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index a1b37d6c78..5a60cb8a65 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.0-alpha-42832';
+$wp_version = '5.0-alpha-42833';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.