diff --git a/guacamole-common-js/src/main/resources/guacamole.js b/guacamole-common-js/src/main/resources/guacamole.js
index 04aae5b50..e0fe0bf8f 100644
--- a/guacamole-common-js/src/main/resources/guacamole.js
+++ b/guacamole-common-js/src/main/resources/guacamole.js
@@ -364,6 +364,14 @@ Guacamole.OutputStream = function(client, index) {
      */
     this.index = index;
 
+    /**
+     * Fired when the stream is being closed due to an error.
+     * 
+     * @param {String} reason A human-readable reason describing the error.
+     * @param {Number} code The error code associated with the error.
+     */
+    this.onerror = null;
+
     /**
      * Writes the given base64-encoded data to this stream as a blob.
      * 
@@ -494,9 +502,12 @@ Guacamole.Client = function(tunnel) {
     // No initial streams 
     var streams = [];
 
-    // Pool of available streams
+    // Pool of available stream indices
     var stream_indices = new Guacamole.IntegerPool();
 
+    // Array of allocated output streams by index
+    var output_streams = [];
+
     tunnel.onerror = function(message) {
         if (guac_client.onerror)
             guac_client.onerror(message);
@@ -682,13 +693,14 @@ Guacamole.Client = function(tunnel) {
 
         // Create new stream
         guac_client.beginFileStream(index, mimetype, filename);
-        var stream = new Guacamole.OutputStream(guac_client, index);
+        var stream = output_streams[index] = new Guacamole.OutputStream(guac_client, index);
 
         // Override close() of stream to automatically free index
         var old_close = stream.close;
         stream.close = function() {
             old_close();
             stream_indices.free(index);
+            delete output_streams[index];
         };
 
         // Return new, overridden stream
@@ -717,7 +729,8 @@ Guacamole.Client = function(tunnel) {
      * is being closed.
      * 
      * @event
-     * @param {String} error A human-readable description of the error.
+     * @param {String} reason A human-readable reason describing the error.
+     * @param {Number} code The error code associated with the error.
      */
     this.onerror = null;
 
@@ -862,6 +875,28 @@ Guacamole.Client = function(tunnel) {
      */
     var instructionHandlers = {
 
+        "abort": function(parameters) {
+
+            var stream_index = parseInt(parameters[0]);
+            var reason = parameters[1];
+            var code = parameters[2];
+
+            // Get stream
+            var stream = output_streams[stream_index];
+
+            // Invalidate stream
+            if (stream) {
+
+                // Signal error if handler defined
+                if (stream.onerror)
+                    stream.onerror(reason, code);
+
+                stream_indices.free(stream_index);
+                delete output_streams[stream_index];
+            }
+
+        },
+
         "arc": function(parameters) {
 
             var layer = getLayer(parseInt(parameters[0]));
@@ -1085,8 +1120,16 @@ Guacamole.Client = function(tunnel) {
         },
  
         "error": function(parameters) {
-            if (guac_client.onerror) guac_client.onerror(parameters[0]);
+
+            var reason = parameters[0];
+            var code = parameters[1];
+
+            // Call handler if defined
+            if (guac_client.onerror)
+                guac_client.onerror(reason, code);
+
             guac_client.disconnect();
+
         },
 
         "end": function(parameters) {
diff --git a/guacamole/src/main/webapp/scripts/client-ui.js b/guacamole/src/main/webapp/scripts/client-ui.js
index c6a5ec082..8904005f5 100644
--- a/guacamole/src/main/webapp/scripts/client-ui.js
+++ b/guacamole/src/main/webapp/scripts/client-ui.js
@@ -1104,12 +1104,21 @@ GuacUI.Client.attach = function(guac) {
             // Open file for writing
             var stream = GuacUI.Client.attachedClient.createFileStream(file.type, file.name);
 
+            var valid = true;
             var bytes = new Uint8Array(reader.result);
             var offset = 0;
+
+            // Invalidate stream on all errors
+            stream.onerror = function() {
+                valid = false;
+            };
            
             // Create upload callback
             function continueUpload() {
 
+                // Abort upload if stream is invalid
+                if (!valid) return false;
+
                 // Encode packet as base64
                 var slice = bytes.subarray(offset, offset+4096);
                 var base64 = _get_base64(slice);