diff --git a/js/deviceserver.js b/js/deviceserver.js
index 7d80a945414cc32dd4ee40ece4fd30f6511296fd..9d28c38322e384c050cbf9d60d2ebdaf9eb803e3 100644
--- a/js/deviceserver.js
+++ b/js/deviceserver.js
@@ -3,7 +3,7 @@
 //    WebSocket device server
 //
 // Neil Gershenfeld 
-// (c) Massachusetts Institute of Technology 2017
+// (c) Massachusetts Institute of Technology 2019
 // 
 // This work may be reproduced, modified, distributed, performed, and 
 // displayed for any purpose, but must acknowledge the mods
@@ -100,7 +100,12 @@ wss.on('connection',function(ws) {
                      else {
                         console.log('done')
                         ws.send('done')
-                        fs.close(file)
+                        fs.close(file,function(err) {
+                           if (err) {
+                              console.log('error: '+err)
+                              ws.send('error: '+err)
+                              }
+                           })
                         }
                      }
                   })