fix hyracks REST error printing
diff --git a/hyracks/hyracks-control/hyracks-control-cc/src/main/java/edu/uci/ics/hyracks/control/cc/job/JobRun.java b/hyracks/hyracks-control/hyracks-control-cc/src/main/java/edu/uci/ics/hyracks/control/cc/job/JobRun.java
index 16f36a6..9cd7886 100644
--- a/hyracks/hyracks-control/hyracks-control-cc/src/main/java/edu/uci/ics/hyracks/control/cc/job/JobRun.java
+++ b/hyracks/hyracks-control/hyracks-control-cc/src/main/java/edu/uci/ics/hyracks/control/cc/job/JobRun.java
@@ -14,6 +14,8 @@
  */
 package edu.uci.ics.hyracks.control.cc.job;
 
+import java.io.PrintWriter;
+import java.io.StringWriter;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -345,7 +347,11 @@
                                 taskAttempt.put("end-time", ta.getEndTime());
                                 List<Exception> exceptions = ta.getExceptions();
                                 if (exceptions != null && !exceptions.isEmpty()) {
-                                    taskAttempt.put("failure-details", exceptions);
+                                    for(Exception exception : exceptions){
+                                        StringWriter exceptionWriter = new StringWriter();
+                                        exception.printStackTrace(new PrintWriter(exceptionWriter));
+                                        taskAttempt.put("failure-details", exceptionWriter.toString());
+                                    }
                                 }
                                 taskAttempts.put(taskAttempt);
                             }