Ticket #25817: 25817.diff

src/wp-admin/includes/class-wp-upgrader.php

@@ -1334 +1334 @@
                         return new WP_Error('up_to_date', $this->strings['up_to_date']);
 
                 $res = $this->fs_connect( array(ABSPATH, WP_CONTENT_DIR) );
-                if ( is_wp_error($res) )
+                if ( ! $res || is_wp_error( $res ) ) {
                         return $res;
+                }
 
                 $wp_dir = trailingslashit($wp_filesystem->abspath());
 
@@ -1899 +1900 @@
                         'attempt_rollback'   => true, /* only available for core updates */
                 ) );
 
+                // if the filesystem is unavailable, false is returned.
+                if ( false === $upgrade_result ) {
+                        $upgrade_result = new WP_Error( 'fs_unavailable', __( 'Could not access filesystem.' ) );                       
+                }
+
                 // Core doesn't output this, so lets append it so we don't get confused
                 if ( 'core' == $type ) {
                         if ( is_wp_error( $upgrade_result ) ) {