diff --git a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java
index 733ef43..f73ad72 100644
--- a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java
+++ b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java
@@ -5764,23 +5764,22 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 					.getTabularResource(tabularResourceId);
 			List<HistoryStep> history = tabularResource.getHistory();
 			long historyId = 0;
-			String opDesc=null, opName=null;
+			String opDesc = null, opName = null;
 			HistoryStep lastStep = null;
 			OpHistory op = null;
-			
+
 			if (history != null && history.size() > 0) {
 				lastStep = history.get(0);
 				if (lastStep != null) {
 					opDesc = lastStep.getOperationDescription();
 					opName = opDesc;
 					historyId = lastStep.getId().getValue();
-					op = new OpHistory(historyId, opName,
-							opDesc, sdf.format(lastStep
-									.getExecutionDate().getTime()));
+					op = new OpHistory(historyId, opName, opDesc,
+							sdf.format(lastStep.getExecutionDate().getTime()));
 				}
 
 			}
-		
+
 			logger.debug("Last Operation Info :" + op);
 			return op;
 
@@ -5815,22 +5814,21 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 					Long.valueOf(trId.getId()));
 			TabularResource tabularResource = service
 					.getTabularResource(tabularResourceId);
-			
+
 			List<HistoryStep> history = tabularResource.getHistory();
 			long historyId = 0;
-			String opDesc=null, opName=null;
+			String opDesc = null, opName = null;
 			HistoryStep lastStep = null;
 			OpHistory op = null;
-			
+
 			if (history != null && history.size() > 0) {
 				lastStep = history.get(0);
 				if (lastStep != null) {
 					opDesc = lastStep.getOperationDescription();
 					opName = opDesc;
 					historyId = lastStep.getId().getValue();
-					op = new OpHistory(historyId, opName,
-							opDesc, sdf.format(lastStep
-									.getExecutionDate().getTime()));
+					op = new OpHistory(historyId, opName, opDesc,
+							sdf.format(lastStep.getExecutionDate().getTime()));
 				}
 
 			}
@@ -5876,9 +5874,9 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 			List<HistoryStep> history = tabularResource.getHistory();
 
 			ArrayList<OpHistory> opHistoryList = new ArrayList<OpHistory>();
-			
+
 			long historyId = 0;
-			String opDesc=null, opName=null;
+			String opDesc = null, opName = null;
 			OpHistory op = null;
 
 			for (HistoryStep step : history) {
@@ -5886,9 +5884,8 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 					historyId = step.getId().getValue();
 					opDesc = step.getOperationDescription();
 					opName = step.getOperationDescription();
-					op = new OpHistory(historyId, opName,
-							opDesc, sdf.format(step
-									.getExecutionDate().getTime()));
+					op = new OpHistory(historyId, opName, opDesc,
+							sdf.format(step.getExecutionDate().getTime()));
 					opHistoryList.add(op);
 				}
 			}
@@ -5931,7 +5928,7 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 			ArrayList<OpHistory> opHistoryList = new ArrayList<OpHistory>();
 
 			long historyId = 0;
-			String opDesc=null, opName=null;
+			String opDesc = null, opName = null;
 			OpHistory op = null;
 
 			for (HistoryStep step : history) {
@@ -5939,13 +5936,12 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 					historyId = step.getId().getValue();
 					opDesc = step.getOperationDescription();
 					opName = step.getOperationDescription();
-					op = new OpHistory(historyId, opName,
-							opDesc, sdf.format(step
-									.getExecutionDate().getTime()));
+					op = new OpHistory(historyId, opName, opDesc,
+							sdf.format(step.getExecutionDate().getTime()));
 					opHistoryList.add(op);
 				}
 			}
-			
+
 			logger.debug("History :" + opHistoryList);
 			return opHistoryList;
 
@@ -5980,22 +5976,25 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 			List<HistoryStep> history = tabularResource.getHistory();
 
 			long historyId = 0;
-			String opDesc=null, opName=null;
+			String opDesc = null, opName = null;
 			OpHistory op = null;
-			RollBackSession rollBackSession=null;
+			RollBackSession rollBackSession = null;
 			if (history != null) {
-				HistoryStep step = history.get(1);
-				if (step != null) {
-					historyId = step.getId().getValue();
-					opDesc= step.getOperationDescription();
-					opName= opDesc;
-					op = new OpHistory(historyId, opName,
-							opDesc, sdf.format(step
-									.getExecutionDate().getTime()));
-					logger.debug("Discard :"+op);
-					rollBackSession=new RollBackSession(trId,historyId);
-					rollBack(rollBackSession);
-					
+				if (history.size() > 1) {
+					HistoryStep step = history.get(history.size() - 2);
+					if (step != null) {
+						historyId = step.getId().getValue();
+						opDesc = step.getOperationDescription();
+						opName = opDesc;
+						op = new OpHistory(historyId, opName, opDesc,
+								sdf.format(step.getExecutionDate().getTime()));
+						logger.debug("Discard :" + op);
+						rollBackSession = new RollBackSession(trId, historyId);
+						rollBack(rollBackSession);
+
+					} else {
+						logger.debug("Discard : step null");
+					}
 				} else {
 					logger.debug("Discard : no previous step exist");
 				}