diff --git a/apps/files/ajax/scan.php b/apps/files/ajax/scan.php
index 3f430cd27e..7d47a538fa 100644
--- a/apps/files/ajax/scan.php
+++ b/apps/files/ajax/scan.php
@@ -49,10 +49,14 @@ foreach ($users as $user) {
 	$scanner = new \OC\Files\Utils\Scanner($user, \OC::$server->getDatabaseConnection());
 	$scanner->listen('\OC\Files\Utils\Scanner', 'scanFile', array($listener, 'file'));
 	$scanner->listen('\OC\Files\Utils\Scanner', 'scanFolder', array($listener, 'folder'));
-	if ($force) {
-		$scanner->scan($dir);
-	} else {
-		$scanner->backgroundScan($dir);
+	try {
+		if ($force) {
+			$scanner->scan($dir);
+		} else {
+			$scanner->backgroundScan($dir);
+		}
+	} catch (\Exception $e) {
+		$eventSource->send('error', get_class($e) . ': ' . $e->getMessage());
 	}
 }
 
diff --git a/apps/files/js/files.js b/apps/files/js/files.js
index 245648a79e..4fdc9eb211 100644
--- a/apps/files/js/files.js
+++ b/apps/files/js/files.js
@@ -333,6 +333,9 @@ function scanFiles(force, dir, users) {
 	scannerEventSource.listen('folder',function(path) {
 		console.log('now scanning ' + path);
 	});
+	scannerEventSource.listen('error',function(message) {
+		console.error('Scanner error: ', message);
+	});
 	scannerEventSource.listen('done',function(count) {
 		scanFiles.scanning=false;
 		console.log('done after ' + count + ' files');
diff --git a/lib/private/files/cache/scanner.php b/lib/private/files/cache/scanner.php
index 7c65c72135..f76ef5ba0d 100644
--- a/lib/private/files/cache/scanner.php
+++ b/lib/private/files/cache/scanner.php
@@ -416,11 +416,21 @@ class Scanner extends BasicEmitter {
 	public function backgroundScan() {
 		$lastPath = null;
 		while (($path = $this->cache->getIncomplete()) !== false && $path !== $lastPath) {
-			$this->scan($path, self::SCAN_RECURSIVE, self::REUSE_ETAG);
-			\OC_Hook::emit('Scanner', 'correctFolderSize', array('path' => $path));
-			if ($this->cacheActive) {
-				$this->cache->correctFolderSize($path);
+			try {
+				$this->scan($path, self::SCAN_RECURSIVE, self::REUSE_ETAG);
+				\OC_Hook::emit('Scanner', 'correctFolderSize', array('path' => $path));
+				if ($this->cacheActive) {
+					$this->cache->correctFolderSize($path);
+				}
+			} catch (\OCP\Files\StorageInvalidException $e) {
+				// skip unavailable storages
+			} catch (\OCP\Files\StorageNotAvailableException $e) {
+				// skip unavailable storages
+			} catch (\OCP\Lock\LockedException $e) {
+				// skip unavailable storages
 			}
+			// FIXME: this won't proceed with the next item, needs revamping of getIncomplete()
+			// to make this possible
 			$lastPath = $path;
 		}
 	}