handle case where fileid is not set

lib/private/connector/sabre/filesplugin.php

@@ -59,7 +59,10 @@ class OC_Connector_Sabre_FilesPlugin extends Sabre_DAV_ServerPlugin
 			unset($requestedProperties[array_search($fileid_propertyname, $requestedProperties)]);
 
 			/** @var $node OC_Connector_Sabre_Node */
-			$returnedProperties[200][$fileid_propertyname] = $node->getFileId();
+			$fileId = $node->getFileId();
+			if (!is_null($fileId)) {
+				$returnedProperties[200][$fileid_propertyname] = $fileId;
+			}
 
 		}
 

lib/private/connector/sabre/node.php

@@ -272,8 +272,13 @@ abstract class OC_Connector_Sabre_Node implements Sabre_DAV_INode, Sabre_DAV_IPr
 	public function getFileId()
 	{
 		$this->getFileinfoCache();
-		$instanceId = OC_Util::getInstanceId();
-		$id = sprintf('%08d', $this->fileinfo_cache['fileid']);
-		return $instanceId . $id;
+
+		if (isset($this->fileinfo_cache['fileid'])) {
+			$instanceId = OC_Util::getInstanceId();
+			$id = sprintf('%08d', $this->fileinfo_cache['fileid']);
+			return $instanceId . $id;
+		}
+
+		return null;
 	}
 }