diff --git src/wp-admin/includes/class-wp-upgrader.php src/wp-admin/includes/class-wp-upgrader.php
index 0ab08b6..019bb47 100644
--- src/wp-admin/includes/class-wp-upgrader.php
+++ src/wp-admin/includes/class-wp-upgrader.php
@@ -1058,11 +1058,14 @@ class Plugin_Upgrader extends WP_Upgrader {
 
 		// Check the folder contains at least 1 valid plugin.
 		$plugins_found = false;
-		foreach ( glob( $working_directory . '*.php' ) as $file ) {
-			$info = get_plugin_data($file, false, false);
-			if ( !empty( $info['Name'] ) ) {
-				$plugins_found = true;
-				break;
+		$files = glob( $working_directory . '*.php' );
+		if ( $files ) {
+			foreach ( $files as $file ) {
+				$info = get_plugin_data( $file, false, false );
+				if ( ! empty( $info['Name'] ) ) {
+					$plugins_found = true;
+					break;
+				}
 			}
 		}
 
diff --git src/wp-admin/includes/update-core.php src/wp-admin/includes/update-core.php
index f6fee79..0cb824a 100644
--- src/wp-admin/includes/update-core.php
+++ src/wp-admin/includes/update-core.php
@@ -1273,8 +1273,11 @@ function _upgrade_422_find_genericons_files_in_folder( $directory ) {
 		$files[] = "{$directory}example.html";
 	}
 
-	foreach ( glob( $directory . '*', GLOB_ONLYDIR ) as $dir ) {
-		$files = array_merge( $files, _upgrade_422_find_genericons_files_in_folder( $dir ) );
+	$dirs = glob( $directory . '*', GLOB_ONLYDIR );
+	if ( $dirs ) {
+		foreach ( $dirs as $dir ) {
+			$files = array_merge( $files, _upgrade_422_find_genericons_files_in_folder( $dir ) );
+		}
 	}
 
 	return $files;
diff --git src/wp-includes/l10n.php src/wp-includes/l10n.php
index 7366e58..7caf879 100644
--- src/wp-includes/l10n.php
+++ src/wp-includes/l10n.php
@@ -774,11 +774,15 @@ function translate_user_role( $name ) {
 function get_available_languages( $dir = null ) {
 	$languages = array();
 
-	foreach( (array)glob( ( is_null( $dir) ? WP_LANG_DIR : $dir ) . '/*.mo' ) as $lang_file ) {
-		$lang_file = basename($lang_file, '.mo');
-		if ( 0 !== strpos( $lang_file, 'continents-cities' ) && 0 !== strpos( $lang_file, 'ms-' ) &&
-			0 !== strpos( $lang_file, 'admin-' ))
-			$languages[] = $lang_file;
+	$lang_files = glob( ( is_null( $dir) ? WP_LANG_DIR : $dir ) . '/*.mo' );
+	if ( $lang_files ) {
+		foreach( $lang_files as $lang_file ) {
+			$lang_file = basename( $lang_file, '.mo' );
+			if ( 0 !== strpos( $lang_file, 'continents-cities' ) && 0 !== strpos( $lang_file, 'ms-' ) &&
+				0 !== strpos( $lang_file, 'admin-' ) ) {
+				$languages[] = $lang_file;
+			}
+		}
 	}
 
 	return $languages;