diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/context/ContextManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/context/ContextManagement.java
index 5956669..5091b7d 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/context/ContextManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/context/ContextManagement.java
@@ -11,13 +11,13 @@ import org.gcube.informationsystem.model.embedded.Header;
 import org.gcube.informationsystem.model.entity.Context;
 import org.gcube.informationsystem.model.relation.IsParentOf;
 import org.gcube.informationsystem.model.relation.Relation;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AlreadyPresentException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextAlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.EntityAvailableInAnotherContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAlreadyPresentException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext;
 import org.gcube.informationsystem.resourceregistry.dbinitialization.DatabaseEnvironment;
 import org.gcube.informationsystem.resourceregistry.er.ERManagement;
@@ -86,7 +86,7 @@ public class ContextManagement extends EntityManagement<Context> {
 	}
 	
 	@Override
-	protected ContextNotFoundException getSpecificElementNotFoundException(ERNotFoundException e) {
+	protected ContextNotFoundException getSpecificElementNotFoundException(NotFoundException e) {
 		return new ContextNotFoundException(e.getMessage(), e.getCause());
 	}
 	
@@ -194,7 +194,7 @@ public class ContextManagement extends EntityManagement<Context> {
 	}
 	
 	@Override
-	protected Vertex reallyCreate() throws ERAlreadyPresentException, ResourceRegistryException {
+	protected Vertex reallyCreate() throws AlreadyPresentException, ResourceRegistryException {
 		SecurityContext securityContext = null;
 		SecurityContext parentSecurityContext = null;
 		
@@ -250,7 +250,7 @@ public class ContextManagement extends EntityManagement<Context> {
 	}
 	
 	@Override
-	protected Vertex reallyUpdate() throws ERNotFoundException, ResourceRegistryException {
+	protected Vertex reallyUpdate() throws NotFoundException, ResourceRegistryException {
 		
 		boolean parentChanged = false;
 		boolean nameChanged = false;
@@ -366,7 +366,7 @@ public class ContextManagement extends EntityManagement<Context> {
 	}
 	
 	@Override
-	protected boolean reallyDelete() throws ERNotFoundException, ResourceRegistryException {
+	protected boolean reallyDelete() throws NotFoundException, ResourceRegistryException {
 		Iterable<Edge> iterable = getElement().getEdges(Direction.OUT);
 		Iterator<Edge> iterator = iterable.iterator();
 		while(iterator.hasNext()) {
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/context/IsParentOfManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/context/IsParentOfManagement.java
index e929b98..968749d 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/context/IsParentOfManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/context/IsParentOfManagement.java
@@ -7,9 +7,9 @@ import org.gcube.informationsystem.model.embedded.PropagationConstraint.AddConst
 import org.gcube.informationsystem.model.embedded.PropagationConstraint.RemoveConstraint;
 import org.gcube.informationsystem.model.relation.IsParentOf;
 import org.gcube.informationsystem.model.relation.Relation;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.RelationAvailableInAnotherContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.isparentof.IsParentOfAlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.isparentof.IsParentOfNotFoundException;
@@ -90,7 +90,7 @@ public class IsParentOfManagement extends RelationManagement<IsParentOf,ContextM
 	}
 	
 	@Override
-	protected IsParentOfNotFoundException getSpecificElementNotFoundException(ERNotFoundException e) {
+	protected IsParentOfNotFoundException getSpecificElementNotFoundException(NotFoundException e) {
 		return new IsParentOfNotFoundException(e.getMessage(), e.getCause());
 	}
 	
@@ -140,12 +140,12 @@ public class IsParentOfManagement extends RelationManagement<IsParentOf,ContextM
 	}
 	
 	@Override
-	public boolean addToContext() throws ERNotFoundException, ContextException {
+	public boolean addToContext() throws NotFoundException, ContextException {
 		throw new UnsupportedOperationException();
 	}
 	
 	@Override
-	public boolean removeFromContext() throws ERNotFoundException, ContextException {
+	public boolean removeFromContext() throws NotFoundException, ContextException {
 		throw new UnsupportedOperationException();
 	}
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagement.java
index 115d5be..5b951f8 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagement.java
@@ -22,11 +22,11 @@ import org.gcube.informationsystem.model.ISManageable;
 import org.gcube.informationsystem.model.embedded.Header;
 import org.gcube.informationsystem.model.entity.Context;
 import org.gcube.informationsystem.model.entity.Entity;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AlreadyPresentException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AvailableInAnotherContextException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAlreadyPresentException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAvailableInAnotherContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.schema.SchemaException;
 import org.gcube.informationsystem.resourceregistry.context.ContextUtility;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext;
@@ -234,9 +234,9 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 	
 	public abstract JSONObject serializeAsJson() throws ResourceRegistryException;
 	
-	protected abstract El reallyCreate() throws ERAlreadyPresentException, ResourceRegistryException;
+	protected abstract El reallyCreate() throws AlreadyPresentException, ResourceRegistryException;
 	
-	public El internalCreate() throws ERAlreadyPresentException, ResourceRegistryException {
+	public El internalCreate() throws AlreadyPresentException, ResourceRegistryException {
 		try {
 			reallyCreate();
 			
@@ -259,9 +259,9 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	protected abstract El reallyUpdate() throws ERNotFoundException, ResourceRegistryException;
+	protected abstract El reallyUpdate() throws NotFoundException, ResourceRegistryException;
 	
-	public El internalUpdate() throws ERNotFoundException, ResourceRegistryException {
+	public El internalUpdate() throws NotFoundException, ResourceRegistryException {
 		try {
 			
 			reallyUpdate();
@@ -280,14 +280,14 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 	public El internalCreateOrUdate() throws ResourceRegistryException {
 		try {
 			return internalUpdate();
-		} catch(ERNotFoundException e) {
+		} catch(NotFoundException e) {
 			return internalCreate();
 		}
 	}
 	
-	protected abstract boolean reallyDelete() throws ERNotFoundException, ResourceRegistryException;
+	protected abstract boolean reallyDelete() throws NotFoundException, ResourceRegistryException;
 	
-	public boolean internalDelete() throws ERNotFoundException, ResourceRegistryException {
+	public boolean internalDelete() throws NotFoundException, ResourceRegistryException {
 		// Added for consistency with create and update addToContext removeFromContext.
 		return reallyDelete();
 	}
@@ -330,24 +330,24 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		this.uuid = HeaderUtility.getHeader(element).getUUID();
 	}
 	
-	protected abstract ERNotFoundException getSpecificElementNotFoundException(ERNotFoundException e);
+	protected abstract NotFoundException getSpecificElementNotFoundException(NotFoundException e);
 	
-	protected abstract ERAvailableInAnotherContextException getSpecificERAvailableInAnotherContextException(
+	protected abstract AvailableInAnotherContextException getSpecificERAvailableInAnotherContextException(
 			String message);
 	
-	protected abstract ERAlreadyPresentException getSpecificERAlreadyPresentException(String message);
+	protected abstract AlreadyPresentException getSpecificERAlreadyPresentException(String message);
 	
-	public El getElement() throws ERNotFoundException, ERAvailableInAnotherContextException, ResourceRegistryException {
+	public El getElement() throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
 		if(element == null) {
 			try {
 				element = retrieveElement();
-			} catch(ERNotFoundException e) {
+			} catch(NotFoundException e) {
 				try {
 					retrieveElementFromAnyContext();
 					throw getSpecificERAvailableInAnotherContextException(erType == null ? accessType.getName()
 							: erType + " with UUID " + uuid + " is available in another "
 									+ Context.class.getSimpleName());
-				} catch(ERAvailableInAnotherContextException e1) {
+				} catch(AvailableInAnotherContextException e1) {
 					throw e1;
 				} catch(Exception e1) {
 					throw e;
@@ -366,14 +366,14 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		return element;
 	}
 	
-	public El retrieveElement() throws ERNotFoundException, ResourceRegistryException {
+	public El retrieveElement() throws NotFoundException, ResourceRegistryException {
 		try {
 			if(uuid == null) {
-				throw new ERNotFoundException("null UUID does not allow to retrieve the Element");
+				throw new NotFoundException("null UUID does not allow to retrieve the Element");
 			}
 			return Utility.getElementByUUID(orientGraph, erType == null ? accessType.getName() : erType, uuid,
 					elementClass);
-		} catch(ERNotFoundException e) {
+		} catch(NotFoundException e) {
 			throw getSpecificElementNotFoundException(e);
 		} catch(ResourceRegistryException e) {
 			throw e;
@@ -382,10 +382,10 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	public El retrieveElementFromAnyContext() throws ERNotFoundException, ResourceRegistryException {
+	public El retrieveElementFromAnyContext() throws NotFoundException, ResourceRegistryException {
 		try {
 			return Utility.getElementByUUIDAsAdmin(erType == null ? accessType.getName() : erType, uuid, elementClass);
-		} catch(ERNotFoundException e) {
+		} catch(NotFoundException e) {
 			throw getSpecificElementNotFoundException(e);
 		} catch(ResourceRegistryException e) {
 			throw e;
@@ -414,7 +414,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 	}
 	
 	public boolean exists()
-			throws ERNotFoundException, ERAvailableInAnotherContextException, ResourceRegistryException {
+			throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
 		try {
 			orientGraph = getWorkingContext().getGraph(PermissionMode.READER);
 			
@@ -434,7 +434,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	public String create() throws ERAlreadyPresentException, ResourceRegistryException {
+	public String create() throws AlreadyPresentException, ResourceRegistryException {
 		
 		try {
 			orientGraph = getWorkingContext().getGraph(PermissionMode.WRITER);
@@ -468,7 +468,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	public String read() throws ERNotFoundException, ERAvailableInAnotherContextException, ResourceRegistryException {
+	public String read() throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
 		try {
 			orientGraph = getWorkingContext().getGraph(PermissionMode.READER);
 			
@@ -488,7 +488,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	public String update() throws ERNotFoundException, ERAvailableInAnotherContextException, ResourceRegistryException {
+	public String update() throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
 		try {
 			orientGraph = getWorkingContext().getGraph(PermissionMode.WRITER);
 			orientGraph.setAutoStartTx(false);
@@ -524,7 +524,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 	}
 	
 	public boolean delete()
-			throws ERNotFoundException, ERAvailableInAnotherContextException, ResourceRegistryException {
+			throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
 		logger.debug("Going to delete {} with UUID {}", accessType.getName(), uuid);
 		
 		try {
@@ -564,7 +564,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	public boolean addToContext() throws ERNotFoundException, ContextException, ResourceRegistryException {
+	public boolean addToContext() throws NotFoundException, ContextException, ResourceRegistryException {
 		logger.info("Going to add {} with UUID {} to Context {}", accessType.getName(), uuid,
 				getWorkingContext().toString());
 		
@@ -598,7 +598,7 @@ public abstract class ERManagement<ERType extends ER, El extends Element> {
 		}
 	}
 	
-	public boolean removeFromContext() throws ERNotFoundException, ContextException, ResourceRegistryException {
+	public boolean removeFromContext() throws NotFoundException, ContextException, ResourceRegistryException {
 		logger.debug("Going to remove {} with UUID {} from actual Context", accessType.getName(), uuid);
 		
 		try {
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagementUtility.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagementUtility.java
index e69042a..f7f6c7b 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagementUtility.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/ERManagementUtility.java
@@ -8,8 +8,8 @@ import org.gcube.informationsystem.model.entity.Resource;
 import org.gcube.informationsystem.model.relation.ConsistsOf;
 import org.gcube.informationsystem.model.relation.IsRelatedTo;
 import org.gcube.informationsystem.model.relation.Relation;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext;
 import org.gcube.informationsystem.resourceregistry.er.entity.EntityManagement;
 import org.gcube.informationsystem.resourceregistry.er.entity.FacetManagement;
@@ -75,10 +75,10 @@ public class ERManagementUtility {
 				Entity.NAME, Relation.NAME));
 	}
 	
-	public static Element getAnyElementByUUID(UUID uuid) throws ERNotFoundException, ResourceRegistryException {
+	public static Element getAnyElementByUUID(UUID uuid) throws NotFoundException, ResourceRegistryException {
 		try {
 			return Utility.getElementByUUIDAsAdmin(null, uuid, Vertex.class);
-		} catch(ERNotFoundException e) {
+		} catch(NotFoundException e) {
 			return Utility.getElementByUUIDAsAdmin(null, uuid, Edge.class);
 		} catch(ResourceRegistryException e) {
 			throw e;
@@ -88,10 +88,10 @@ public class ERManagementUtility {
 	}
 	
 	private static Element getAnyElementByUUID(OrientGraph orientGraph, UUID uuid)
-			throws ERNotFoundException, ResourceRegistryException {
+			throws NotFoundException, ResourceRegistryException {
 		try {
 			return Utility.getElementByUUID(orientGraph, null, uuid, Vertex.class);
-		} catch(ERNotFoundException e) {
+		} catch(NotFoundException e) {
 			return Utility.getElementByUUID(orientGraph, null, uuid, Edge.class);
 		} catch(ResourceRegistryException e) {
 			throw e;
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java
index be30424..9406ef2 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java
@@ -8,11 +8,11 @@ import org.codehaus.jettison.json.JSONObject;
 import org.gcube.informationsystem.model.AccessType;
 import org.gcube.informationsystem.model.entity.Entity;
 import org.gcube.informationsystem.model.relation.Relation;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AvailableInAnotherContextException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.EntityAlreadyPresentException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAvailableInAnotherContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext;
 import org.gcube.informationsystem.resourceregistry.er.ERManagement;
 import org.gcube.informationsystem.resourceregistry.er.ERManagementUtility;
@@ -135,17 +135,17 @@ public abstract class EntityManagement<E extends Entity> extends ERManagement<E,
 					}
 				}
 				
-			} catch(ERNotFoundException e) {
+			} catch(NotFoundException e) {
 				try {
 					Element el = ERManagementUtility.getAnyElementByUUID(uuid);
 					String error = String.format("UUID %s is already used by another %s. This is not allowed.",
 							uuid.toString(), (el instanceof Vertex) ? Entity.NAME : Relation.NAME);
 					throw getSpecificERAvailableInAnotherContextException(error);
 					
-				} catch(ERNotFoundException e1) {
+				} catch(NotFoundException e1) {
 					// OK the UUID is not already used.
 				}
-			} catch(ERAvailableInAnotherContextException e) {
+			} catch(AvailableInAnotherContextException e) {
 				throw e;
 			}
 			
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/FacetManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/FacetManagement.java
index e92748d..396cd1c 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/FacetManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/FacetManagement.java
@@ -3,11 +3,11 @@ package org.gcube.informationsystem.resourceregistry.er.entity;
 import org.codehaus.jettison.json.JSONObject;
 import org.gcube.informationsystem.model.AccessType;
 import org.gcube.informationsystem.model.entity.Facet;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.facet.FacetAlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.facet.FacetAvailableInAnotherContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.facet.FacetNotFoundException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext;
 import org.gcube.informationsystem.resourceregistry.er.ERManagement;
 
@@ -28,7 +28,7 @@ public class FacetManagement extends EntityManagement<Facet> {
 	}
 	
 	@Override
-	protected FacetNotFoundException getSpecificElementNotFoundException(ERNotFoundException e) {
+	protected FacetNotFoundException getSpecificElementNotFoundException(NotFoundException e) {
 		return new FacetNotFoundException(e.getMessage(), e.getCause());
 	}
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java
index cd9525b..943cc0e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java
@@ -9,11 +9,11 @@ import org.gcube.informationsystem.model.AccessType;
 import org.gcube.informationsystem.model.entity.Resource;
 import org.gcube.informationsystem.model.relation.ConsistsOf;
 import org.gcube.informationsystem.model.relation.IsRelatedTo;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.resource.ResourceAlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.resource.ResourceAvailableInAnotherContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.entity.resource.ResourceNotFoundException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.rest.AccessPath;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext.PermissionMode;
@@ -50,7 +50,7 @@ public class ResourceManagement extends EntityManagement<Resource> {
 	}
 	
 	@Override
-	protected ResourceNotFoundException getSpecificElementNotFoundException(ERNotFoundException e) {
+	protected ResourceNotFoundException getSpecificElementNotFoundException(NotFoundException e) {
 		return new ResourceNotFoundException(e.getMessage(), e.getCause());
 	}
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/ConsistsOfManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/ConsistsOfManagement.java
index 10a61dc..566753f 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/ConsistsOfManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/ConsistsOfManagement.java
@@ -2,8 +2,8 @@ package org.gcube.informationsystem.resourceregistry.er.relation;
 
 import org.gcube.informationsystem.model.AccessType;
 import org.gcube.informationsystem.model.relation.ConsistsOf;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.consistsOf.ConsistsOfAlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.consistsOf.ConsistsOfAvailableInAnotherContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.consistsOf.ConsistsOfNotFoundException;
@@ -28,7 +28,7 @@ public class ConsistsOfManagement extends RelationManagement<ConsistsOf,Resource
 	}
 	
 	@Override
-	protected ConsistsOfNotFoundException getSpecificElementNotFoundException(ERNotFoundException e) {
+	protected ConsistsOfNotFoundException getSpecificElementNotFoundException(NotFoundException e) {
 		return new ConsistsOfNotFoundException(e.getMessage(), e.getCause());
 	}
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/IsRelatedToManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/IsRelatedToManagement.java
index 18bfb56..44075a8 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/IsRelatedToManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/IsRelatedToManagement.java
@@ -2,8 +2,8 @@ package org.gcube.informationsystem.resourceregistry.er.relation;
 
 import org.gcube.informationsystem.model.AccessType;
 import org.gcube.informationsystem.model.relation.IsRelatedTo;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.isrelatedto.IsRelatedToAlreadyPresentException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.isrelatedto.IsRelatedToAvailableInAnotherContextException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.isrelatedto.IsRelatedToNotFoundException;
@@ -27,7 +27,7 @@ public class IsRelatedToManagement extends RelationManagement<IsRelatedTo,Resour
 	}
 	
 	@Override
-	protected IsRelatedToNotFoundException getSpecificElementNotFoundException(ERNotFoundException e) {
+	protected IsRelatedToNotFoundException getSpecificElementNotFoundException(NotFoundException e) {
 		return new IsRelatedToNotFoundException(e.getMessage(), e.getCause());
 	}
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java
index addc9c5..e72f161 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java
@@ -18,9 +18,9 @@ import org.gcube.informationsystem.model.entity.Entity;
 import org.gcube.informationsystem.model.entity.Facet;
 import org.gcube.informationsystem.model.entity.Resource;
 import org.gcube.informationsystem.model.relation.Relation;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.relation.RelationNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.schema.SchemaException;
 import org.gcube.informationsystem.resourceregistry.context.ContextUtility;
@@ -552,7 +552,7 @@ public abstract class RelationManagement<R extends Relation, S extends EntityMan
 	}
 	
 	@Override
-	public boolean addToContext() throws ERNotFoundException, ContextException {
+	public boolean addToContext() throws NotFoundException, ContextException {
 		logger.debug("Going to add {} with UUID {} to actual Context", accessType.getName(), uuid);
 		
 		try {
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/Access.java b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/Access.java
index 4271ecb..59b0eb4 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/Access.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/Access.java
@@ -22,10 +22,10 @@ import org.gcube.common.authorization.library.provider.CalledMethodProvider;
 import org.gcube.informationsystem.model.entity.Facet;
 import org.gcube.informationsystem.model.relation.ConsistsOf;
 import org.gcube.informationsystem.resourceregistry.ResourceInitializer;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AvailableInAnotherContextException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.context.ContextNotFoundException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAvailableInAnotherContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.query.InvalidQueryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.schema.SchemaNotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.rest.AccessPath;
@@ -94,7 +94,7 @@ public class Access {
 	@HEAD
 	@Path(AccessPath.INSTANCE_PATH_PART + "/" + "{" + TYPE_PATH_PARAM + "}" + "/{" + ID_PATH_PARAM + "}")
 	public Response exists(@PathParam(TYPE_PATH_PARAM) String type, @PathParam(ID_PATH_PARAM) String id)
-			throws ERNotFoundException, ERAvailableInAnotherContextException, ResourceRegistryException {
+			throws NotFoundException, AvailableInAnotherContextException, ResourceRegistryException {
 		CalledMethodProvider.instance.set(HTTPMETHOD.HEAD.name() + " /" + AccessPath.ACCESS_PATH_PART + "/"
 				+ AccessPath.INSTANCE_PATH_PART + "/" + type + "/{" + ID_PATH_PARAM + "}");
 		
@@ -117,9 +117,9 @@ public class Access {
 				// anyway adding it for safety reason
 				return Response.status(Status.NOT_FOUND).build();
 			}
-		} catch(ERNotFoundException e) {
+		} catch(NotFoundException e) {
 			return Response.status(Status.NOT_FOUND).build();
-		} catch(ERAvailableInAnotherContextException e) {
+		} catch(AvailableInAnotherContextException e) {
 			return Response.status(Status.FORBIDDEN).build();
 		} catch(ResourceRegistryException e) {
 			throw e;
@@ -134,7 +134,7 @@ public class Access {
 	@Path(AccessPath.INSTANCE_PATH_PART + "/" + "{" + TYPE_PATH_PARAM + "}" + "/{" + ID_PATH_PARAM + "}")
 	@Produces(ResourceInitializer.APPLICATION_JSON_CHARSET_UTF_8)
 	public String getInstance(@PathParam(TYPE_PATH_PARAM) String type, @PathParam(ID_PATH_PARAM) String id)
-			throws ERNotFoundException, ResourceRegistryException {
+			throws NotFoundException, ResourceRegistryException {
 		
 		CalledMethodProvider.instance.set(HTTPMETHOD.GET.name() + " /" + AccessPath.ACCESS_PATH_PART + "/"
 				+ AccessPath.INSTANCE_PATH_PART + "/" + type + "/{" + ID_PATH_PARAM + "}");
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ERManager.java b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ERManager.java
index c138c3b..f984efb 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ERManager.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ERManager.java
@@ -53,13 +53,13 @@ public class ERManager {
 	 * 
 	 */
 	@PUT
-	@Path(ERPath.FACET_PATH_PART + "/{" + TYPE_PATH_PARAM + "}")
+	@Path(ERPath.FACETS_PATH_PART + "/{" + TYPE_PATH_PARAM + "}")
 	@Consumes({MediaType.TEXT_PLAIN, ResourceInitializer.APPLICATION_JSON_CHARSET_UTF_8})
 	@Produces(ResourceInitializer.APPLICATION_JSON_CHARSET_UTF_8)
 	public Response createFacet(@PathParam(TYPE_PATH_PARAM) String type, String json)
 			throws FacetAlreadyPresentException, ResourceRegistryException {
 		CalledMethodProvider.instance
-				.set(HTTPMETHOD.PUT.name() + " /" + ERPath.ER_PATH_PART + "/" + ERPath.FACET_PATH_PART + "/" + type);
+				.set(HTTPMETHOD.PUT.name() + " /" + ERPath.ER_PATH_PART + "/" + ERPath.FACETS_PATH_PART + "/" + type);
 		logger.info("Requested to create {} of type {}", Facet.NAME, type);
 		logger.trace("Requested to create {} of type {} defined by {} ", Facet.NAME, type, json);
 		FacetManagement facetManagement = new FacetManagement();
@@ -77,13 +77,13 @@ public class ERManager {
 	 * 
 	 */
 	@POST
-	@Path(ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}")
+	@Path(ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}")
 	@Consumes({MediaType.TEXT_PLAIN, ResourceInitializer.APPLICATION_JSON_CHARSET_UTF_8})
 	@Produces(ResourceInitializer.APPLICATION_JSON_CHARSET_UTF_8)
 	public String updateFacet(@PathParam(ID_PATH_PARAM) String uuid, String json)
 			throws FacetNotFoundException, ResourceRegistryException {
 		CalledMethodProvider.instance.set(HTTPMETHOD.POST.name() + " /" + ERPath.ER_PATH_PART + "/"
-				+ ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}");
+				+ ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}");
 		logger.info("Requested to update {} with id {}", Facet.NAME, uuid);
 		logger.trace("Requested to update {} with id {} with json {}", Facet.NAME, uuid, json);
 		FacetManagement facetManagement = new FacetManagement();
@@ -97,11 +97,11 @@ public class ERManager {
 	 * 
 	 */
 	@DELETE
-	@Path(ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}")
+	@Path(ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}")
 	public boolean deleteFacet(@PathParam(ID_PATH_PARAM) String uuid)
 			throws FacetNotFoundException, ResourceRegistryException {
 		CalledMethodProvider.instance.set(HTTPMETHOD.DELETE.name() + " /" + ERPath.ER_PATH_PART + "/"
-				+ ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}");
+				+ ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}");
 		logger.info("Requested to delete {} with id {}", Facet.NAME, uuid);
 		FacetManagement facetManagement = new FacetManagement();
 		facetManagement.setUUID(UUID.fromString(uuid));
@@ -273,11 +273,11 @@ public class ERManager {
 	 * 
 	 */
 	@POST
-	@Path(ERPath.ADD_PATH_PART + "/" + ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}")
+	@Path(ERPath.ADD_PATH_PART + "/" + ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}")
 	public boolean addFacetToContext(@PathParam(ID_PATH_PARAM) String uuid)
 			throws FacetNotFoundException, ContextNotFoundException, ResourceRegistryException {
 		CalledMethodProvider.instance.set(HTTPMETHOD.POST.name() + " /" + ERPath.ER_PATH_PART + "/"
-				+ ERPath.ADD_PATH_PART + "/" + ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}");
+				+ ERPath.ADD_PATH_PART + "/" + ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}");
 		logger.info("Requested to add {} with UUID {} to current {}", Facet.NAME, uuid, Context.NAME);
 		FacetManagement facetManagement = new FacetManagement();
 		facetManagement.setUUID(UUID.fromString(uuid));
@@ -307,11 +307,11 @@ public class ERManager {
 	 * 
 	 */
 	@POST
-	@Path(ERPath.REMOVE_PATH_PART + "/" + ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}")
+	@Path(ERPath.REMOVE_PATH_PART + "/" + ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}")
 	public boolean removeFacetFromContext(@PathParam(ID_PATH_PARAM) String uuid)
 			throws FacetNotFoundException, ContextNotFoundException, ResourceRegistryException {
 		CalledMethodProvider.instance.set(HTTPMETHOD.POST.name() + " /" + ERPath.ER_PATH_PART + "/"
-				+ ERPath.REMOVE_PATH_PART + "/" + ERPath.FACET_PATH_PART + "/{" + ID_PATH_PARAM + "}");
+				+ ERPath.REMOVE_PATH_PART + "/" + ERPath.FACETS_PATH_PART + "/{" + ID_PATH_PARAM + "}");
 		logger.info("Requested to remove {} with UUID {} from current {}", Facet.NAME, uuid, Context.NAME);
 		FacetManagement facetManagement = new FacetManagement();
 		facetManagement.setUUID(UUID.fromString(uuid));
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ResourceRegistryExceptionMapper.java b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ResourceRegistryExceptionMapper.java
index 71a3200..7e3bc3b 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ResourceRegistryExceptionMapper.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/ResourceRegistryExceptionMapper.java
@@ -6,10 +6,10 @@ import javax.ws.rs.core.Response.Status;
 import javax.ws.rs.ext.ExceptionMapper;
 import javax.ws.rs.ext.Provider;
 
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AlreadyPresentException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.AvailableInAnotherContextException;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAlreadyPresentException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERAvailableInAnotherContextException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 
 /**
  * @author Luca Frosini (ISTI - CNR)
@@ -22,11 +22,11 @@ public class ResourceRegistryExceptionMapper implements ExceptionMapper<Resource
 		
 		Status status = Status.BAD_REQUEST;
 		
-		if(ERNotFoundException.class.isAssignableFrom(exception.getClass())) {
+		if(NotFoundException.class.isAssignableFrom(exception.getClass())) {
 			status = Status.NOT_FOUND;
-		} else if(ERAlreadyPresentException.class.isAssignableFrom(exception.getClass())) {
+		} else if(AlreadyPresentException.class.isAssignableFrom(exception.getClass())) {
 			status = Status.CONFLICT;
-		} else if(ERAvailableInAnotherContextException.class.isAssignableFrom(exception.getClass())) {
+		} else if(AvailableInAnotherContextException.class.isAssignableFrom(exception.getClass())) {
 			status = Status.FORBIDDEN;
 		} else if(exception.getClass() == ResourceRegistryException.class) {
 			status = Status.INTERNAL_SERVER_ERROR;
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java b/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java
index 100a3ca..0e480c9 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java
@@ -12,8 +12,8 @@ import org.gcube.informationsystem.model.embedded.Embedded;
 import org.gcube.informationsystem.model.embedded.Header;
 import org.gcube.informationsystem.model.entity.Entity;
 import org.gcube.informationsystem.model.relation.Relation;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.NotFoundException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
-import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
 import org.gcube.informationsystem.resourceregistry.context.ContextUtility;
 import org.gcube.informationsystem.resourceregistry.context.security.AdminSecurityContext;
 import org.gcube.informationsystem.resourceregistry.context.security.SecurityContext.PermissionMode;
@@ -85,7 +85,7 @@ public class Utility {
 	}
 	
 	public static <El extends Element> El getElementByUUIDAsAdmin(String elementType, UUID uuid,
-			Class<? extends El> clz) throws ERNotFoundException, ResourceRegistryException {
+			Class<? extends El> clz) throws NotFoundException, ResourceRegistryException {
 		OrientGraphNoTx orientGraphNoTx = null;
 		try {
 			AdminSecurityContext adminSecurityContext = ContextUtility.getAdminSecurityContext();
@@ -99,7 +99,7 @@ public class Utility {
 	}
 	
 	public static <El extends Element> El getElementByUUID(Graph graph, String elementType, UUID uuid,
-			Class<? extends El> clz) throws ERNotFoundException, ResourceRegistryException {
+			Class<? extends El> clz) throws NotFoundException, ResourceRegistryException {
 		
 		if(elementType == null || elementType.compareTo("") == 0) {
 			if(Vertex.class.isAssignableFrom(clz)) {
@@ -120,7 +120,7 @@ public class Utility {
 		if(elements == null || !elements.iterator().hasNext()) {
 			String error = String.format("No %s with UUID %s was found", elementType, uuid.toString());
 			logger.info(error);
-			throw new ERNotFoundException(error);
+			throw new NotFoundException(error);
 		}
 		
 		Iterator<El> iterator = elements.iterator();