diff --git a/.project b/.project
index 6f033c9..6677ce2 100644
--- a/.project
+++ b/.project
@@ -16,12 +16,12 @@
 			</arguments>
 		</buildCommand>
 		<buildCommand>
-			<name>org.eclipse.m2e.core.maven2Builder</name>
+			<name>org.eclipse.wst.validation.validationbuilder</name>
 			<arguments>
 			</arguments>
 		</buildCommand>
 		<buildCommand>
-			<name>org.eclipse.wst.validation.validationbuilder</name>
+			<name>org.eclipse.m2e.core.maven2Builder</name>
 			<arguments>
 			</arguments>
 		</buildCommand>
diff --git a/src/main/java/org/gcube/data/access/storagehub/StorageHub.java b/src/main/java/org/gcube/data/access/storagehub/StorageHub.java
index 342d99a..da500a3 100644
--- a/src/main/java/org/gcube/data/access/storagehub/StorageHub.java
+++ b/src/main/java/org/gcube/data/access/storagehub/StorageHub.java
@@ -6,6 +6,7 @@ import java.util.Set;
 import javax.ws.rs.Path;
 import javax.ws.rs.core.Application;
 
+import org.gcube.common.gxrest.response.entity.SerializableErrorEntityTextWriter;
 import org.gcube.data.access.storagehub.services.ACLManager;
 import org.gcube.data.access.storagehub.services.GroupManager;
 import org.gcube.data.access.storagehub.services.ItemSharing;
@@ -29,8 +30,8 @@ public class StorageHub extends Application {
         classes.add(ACLManager.class);
         classes.add(ItemSharing.class);
         classes.add(UserManager.class);
-        classes.add(GroupManager.class); 
-        //classes.add(AuthorizationExceptionMapper.class);
+        classes.add(GroupManager.class);
+        classes.add(SerializableErrorEntityTextWriter.class);
         return classes;
     }
 
diff --git a/src/main/java/org/gcube/data/access/storagehub/Utils.java b/src/main/java/org/gcube/data/access/storagehub/Utils.java
index 2ad6643..41178f8 100644
--- a/src/main/java/org/gcube/data/access/storagehub/Utils.java
+++ b/src/main/java/org/gcube/data/access/storagehub/Utils.java
@@ -19,6 +19,8 @@ import javax.jcr.NodeIterator;
 import javax.jcr.PathNotFoundException;
 import javax.jcr.RepositoryException;
 import javax.jcr.Session;
+import javax.jcr.lock.Lock;
+import javax.jcr.lock.LockException;
 import javax.jcr.version.Version;
 
 import org.apache.commons.io.FilenameUtils;
@@ -27,6 +29,7 @@ import org.gcube.common.authorization.library.provider.AuthorizationProvider;
 import org.gcube.common.storagehub.model.Excludes;
 import org.gcube.common.storagehub.model.Paths;
 import org.gcube.common.storagehub.model.exceptions.BackendGenericError;
+import org.gcube.common.storagehub.model.exceptions.ItemLockedException;
 import org.gcube.common.storagehub.model.items.AbstractFileItem;
 import org.gcube.common.storagehub.model.items.FolderItem;
 import org.gcube.common.storagehub.model.items.GCubeItem;
@@ -76,13 +79,35 @@ public class Utils {
 	}
 
 
+	public static void acquireLockWithWait(Session ses, String nodePath, boolean isDeep, String login, int maxTries) throws RepositoryException, ItemLockedException {
+
+		Lock lock = null;
+		int tries = 0;
+		while(lock==null && tries<=maxTries) {
+			try {
+				lock = ses.getWorkspace().getLockManager().lock(nodePath, isDeep, true, 0,login);
+				logger.info("lock acquired(try n. {})", tries);
+			}catch (LockException e) {
+				try {
+					if (maxTries>=tries) {
+						int waitTime = (int)(Math.random()*5000);
+						logger.info("lock NOT acquired, waiting (try n. {}) for {}", tries, waitTime);
+						Thread.sleep(waitTime);
+					}
+				} catch (InterruptedException e1) {}
+				tries++;
+			}
+		}
+
+		if (lock==null) throw new ItemLockedException("the item is locked");
+	}
 
 
 
 	public static <T extends Item> List<T> getItemList(Node parent, List<String> excludes, Range range, boolean showHidden, Class<? extends Item> nodeTypeToInclude) throws RepositoryException, BackendGenericError{
 
 		logger.debug("getting children of node {}", parent.getIdentifier());
-		
+
 		List<T> returnList = new ArrayList<T>();
 		long start = System.currentTimeMillis();
 		NodeIterator iterator = parent.getNodes();
@@ -95,12 +120,12 @@ public class Utils {
 			Node current = iterator.nextNode();
 
 			logger.debug("current node "+current.getName());
-			
+
 			if (isToExclude(current, showHidden))
 				continue;
-			
+
 			logger.debug("current node not excluded "+current.getName());
-			
+
 			if (range==null || (count>=range.getStart() && returnList.size()<range.getLimit())) {
 				T item = node2Item.getFilteredItem(current, excludes, nodeTypeToInclude);
 				if (item==null) continue;
@@ -129,7 +154,7 @@ public class Utils {
 	public static org.gcube.common.storagehub.model.Path getHome(String login){
 		return Paths.getPath(String.format("/Home/%s",login));
 	}
-	
+
 	public static StorageClient getStorageClient(String login){
 		return new StorageClient(SERVICE_CLASS, SERVICE_NAME, login, AccessType.SHARED, MemoryType.PERSISTENT);
 
@@ -211,7 +236,7 @@ public class Utils {
 	public static boolean hasSharedChildren(Node node) throws RepositoryException, BackendGenericError{
 		Node2ItemConverter node2Item = new Node2ItemConverter();
 		NodeIterator children = node.getNodes();
-		
+
 		while (children.hasNext()) {
 			Node child= children.nextNode();
 			if (node2Item.checkNodeType(child, SharedFolder.class)) return true;
@@ -243,7 +268,7 @@ public class Utils {
 		}
 
 	}
-	
+
 	public static String checkExistanceAndGetUniqueName(Session ses, Node destination, String name) throws BackendGenericError{
 		try {
 			destination.getNode(name);
@@ -277,11 +302,11 @@ public class Utils {
 			throw new BackendGenericError(e);
 		}
 	}
-	
+
 	public static Node createFolderInternally(Session ses, Node destinationNode, String name, String description, boolean hidden, String login, AccountingHandler accountingHandler) throws BackendGenericError {
-		
+
 		String uniqueName = Utils.checkExistanceAndGetUniqueName(ses, destinationNode, name);
-		
+
 		FolderItem item = new FolderItem();
 		Calendar now = Calendar.getInstance();
 		item.setName(uniqueName);
@@ -294,18 +319,18 @@ public class Utils {
 		item.setLastModifiedBy(login);
 		item.setOwner(login);
 		item.setPublicItem(false);
-		
+
 		//to inherit hidden property
 		//item.setHidden(destinationItem.isHidden());
-		
+
 		Node newNode = new Item2NodeConverter().getNode(destinationNode, item);
 		if (accountingHandler!=null)
 			accountingHandler.createFolderAddObj(name, item.getClass().getSimpleName(), null, ses, newNode, false);
 		return newNode;
 	}
-	
+
 	public static Node createGcubeItemInternally(Session ses, Node destinationNode, String name, String description, String login, GCubeItem gcubeItem, AccountingHandler accountingHandler) throws BackendGenericError {
-						
+
 		Calendar now = Calendar.getInstance();
 		gcubeItem.setName(name);
 		gcubeItem.setTitle(name);
@@ -324,7 +349,7 @@ public class Utils {
 		//accountingHandler.createFolderAddObj(name, item.getClass().getSimpleName(), null, ses, newNode, false);
 		return newNode;
 	}
-	
+
 	public static void setPropertyOnChangeNode(Node node, String login, ItemAction action) throws RepositoryException {
 		node.setProperty(NodeProperty.LAST_MODIFIED.toString(), Calendar.getInstance());
 		node.setProperty(NodeProperty.LAST_MODIFIED_BY.toString(), login);
diff --git a/src/main/java/org/gcube/data/access/storagehub/handlers/Item2NodeConverter.java b/src/main/java/org/gcube/data/access/storagehub/handlers/Item2NodeConverter.java
index 750ce11..9aa6aab 100644
--- a/src/main/java/org/gcube/data/access/storagehub/handlers/Item2NodeConverter.java
+++ b/src/main/java/org/gcube/data/access/storagehub/handlers/Item2NodeConverter.java
@@ -6,15 +6,14 @@ import java.util.Calendar;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
 import java.util.Map.Entry;
+import java.util.Set;
 
 import javax.inject.Singleton;
 import javax.jcr.ItemExistsException;
 import javax.jcr.Node;
 import javax.jcr.PathNotFoundException;
 import javax.jcr.RepositoryException;
-import javax.jcr.Session;
 import javax.jcr.Value;
 
 import org.apache.jackrabbit.util.Text;
diff --git a/src/main/java/org/gcube/data/access/storagehub/services/ItemsCreator.java b/src/main/java/org/gcube/data/access/storagehub/services/ItemsCreator.java
index 98594b5..c528f7c 100644
--- a/src/main/java/org/gcube/data/access/storagehub/services/ItemsCreator.java
+++ b/src/main/java/org/gcube/data/access/storagehub/services/ItemsCreator.java
@@ -125,7 +125,7 @@ public class ItemsCreator {
 			Node destination;
 			try {
 				destination = ses.getNodeByIdentifier(id);
-			}catch(ItemNotFoundException inf) {
+			}catch(RepositoryException inf) {
 				throw new IdNotFoundException(id);
 			}
 
@@ -134,11 +134,7 @@ public class ItemsCreator {
 
 			authChecker.checkWriteAuthorizationControl(ses, destination.getIdentifier(), true);
 
-			try {
-				ses.getWorkspace().getLockManager().lock(destination.getPath(), false, true, 0,login);
-			}catch (LockException le) {
-				throw new ItemLockedException(le);
-			}
+			Utils.acquireLockWithWait(ses, destination.getPath(), false, login, 10);
 
 			Node newNode;
 			try {
@@ -152,7 +148,7 @@ public class ItemsCreator {
 			toReturn =  newNode.getIdentifier();
 		}catch(StorageHubException she ){
 			log.error(she.getErrorMessage(), she);
-			GXOutboundErrorResponse.throwException(she, Response.Status.fromStatusCode(she.getStatus()));
+			GXOutboundErrorResponse.throwExceptionWithTrace(she, 20, Response.Status.fromStatusCode(she.getStatus()),MediaType.TEXT_PLAIN_TYPE);
 		}catch(RepositoryException re ){
 			log.error("jcr error creating item", re);
 			GXOutboundErrorResponse.throwException(new BackendGenericError("jcr error creating item", re));
@@ -189,12 +185,9 @@ public class ItemsCreator {
 
 			authChecker.checkWriteAuthorizationControl(ses, destination.getIdentifier(), true);
 
-			try {
-				ses.getWorkspace().getLockManager().lock(destination.getPath(), false, true, 0,login);
-			}catch (LockException le) {
-				throw new ItemLockedException(le);
-			}
-
+			
+			Utils.acquireLockWithWait(ses, destination.getPath(), false, login, 10);
+			
 			Node newNode;
 			try {
 				newNode = Utils.createGcubeItemInternally(ses, destination, item.getName(), item.getDescription(), login, item, accountingHandler);
@@ -300,18 +293,21 @@ public class ItemsCreator {
 				log.trace("replacing content of class {}",item.getContent().getClass());
 				item2Node.replaceContent(newNode,item, ItemAction.UPDATED);
 				accountingHandler.createFileUpdated(item.getTitle(), ses, newNode, false);
+				ses.save();
 			}finally {
 				ses.getWorkspace().getLockManager().unlock(newNode.getPath());
 			}
 		}catch(PathNotFoundException pnf) {
 			authChecker.checkWriteAuthorizationControl(ses, destinationNode.getIdentifier(), true);
 			try {
-				ses.getWorkspace().getLockManager().lock(destinationNode.getPath(), false, true, 0,login);
+				log.debug("trying to acquire lock");
+				Utils.acquireLockWithWait(ses, destinationNode.getPath(), false, login, 10);
 			}catch (LockException le) {
 				throw new ItemLockedException(le);
 			}
 			try {
 				newNode = item2Node.getNode(destinationNode, item);	
+				ses.save();
 			}finally {
 				ses.getWorkspace().getLockManager().unlock(destinationNode.getPath());
 			}
diff --git a/src/main/java/org/gcube/data/access/storagehub/services/ItemsManager.java b/src/main/java/org/gcube/data/access/storagehub/services/ItemsManager.java
index fc7373f..d8bcd22 100644
--- a/src/main/java/org/gcube/data/access/storagehub/services/ItemsManager.java
+++ b/src/main/java/org/gcube/data/access/storagehub/services/ItemsManager.java
@@ -133,7 +133,7 @@ public class ItemsManager {
 			toReturn = node2Item.getItem(node, excludes);
 		}catch (ItemNotFoundException e) {
 			log.error("id {} not found",id,e);
-			GXOutboundErrorResponse.throwException(new IdNotFoundException("id not found", e), Status.NOT_FOUND);
+			GXOutboundErrorResponse.throwException(new IdNotFoundException(id, e), Status.NOT_FOUND);
 		}catch(RepositoryException re){
 			log.error("jcr error getting item", re);
 			GXOutboundErrorResponse.throwException(new BackendGenericError("jcr error searching item", re));
@@ -177,7 +177,7 @@ public class ItemsManager {
 			}
 		}catch (ItemNotFoundException e) {
 			log.error("id {} not found",id,e);
-			GXOutboundErrorResponse.throwException(new IdNotFoundException("id not found", e), Status.NOT_FOUND);
+			GXOutboundErrorResponse.throwException(new IdNotFoundException(id, e), Status.NOT_FOUND);
 		}catch(RepositoryException re){
 			log.error("jcr error searching item", re);
 			GXOutboundErrorResponse.throwException(new BackendGenericError("jcr error searching item", re));
@@ -207,7 +207,7 @@ public class ItemsManager {
 			toReturn = Utils.getItemCount(ses.getNodeByIdentifier(id), showHidden==null?false:showHidden, nodeType!=null ? ClassHandler.instance().get(nodeType) : null);
 		}catch (ItemNotFoundException e) {
 			log.error("id {} not found",id,e);
-			GXOutboundErrorResponse.throwException(new IdNotFoundException("id not found", e), Status.NOT_FOUND);
+			GXOutboundErrorResponse.throwException(new IdNotFoundException(id, e), Status.NOT_FOUND);
 		}catch(RuntimeException | RepositoryException re){
 			log.error("jcr error counting item", re);
 			GXOutboundErrorResponse.throwException(new BackendGenericError(re));
@@ -234,7 +234,7 @@ public class ItemsManager {
 			toReturn = Utils.getItemList(ses.getNodeByIdentifier(id), excludes, null, showHidden==null?false:showHidden, nodeType!=null ? ClassHandler.instance().get(nodeType) : null);
 		}catch (ItemNotFoundException e) {
 			log.error("id {} not found",id,e);
-			GXOutboundErrorResponse.throwException(new IdNotFoundException("id not found", e), Status.NOT_FOUND);
+			GXOutboundErrorResponse.throwException(new IdNotFoundException(id, e), Status.NOT_FOUND);
 		}catch(RepositoryException re){
 			log.error("jcr error getting children", re);
 			GXOutboundErrorResponse.throwException(new BackendGenericError(re));
@@ -262,7 +262,7 @@ public class ItemsManager {
 			toReturn = Utils.getItemList(ses.getNodeByIdentifier(id), excludes, new Range(start, limit),showHidden==null?false:showHidden, nodeType!=null ? ClassHandler.instance().get(nodeType) : null);
 		}catch (ItemNotFoundException e) {
 			log.error("id {} not found",id,e);
-			GXOutboundErrorResponse.throwException(new IdNotFoundException("id not found", e), Status.NOT_FOUND);
+			GXOutboundErrorResponse.throwException(new IdNotFoundException(id, e), Status.NOT_FOUND);
 		}catch(RepositoryException re){
 			log.error("jcr error getting paged children", re);
 			GXOutboundErrorResponse.throwException(new BackendGenericError(re));