diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java
index 9df5070..3b8167a 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/base/ElementManagement.java
@@ -792,7 +792,7 @@ public abstract class ElementManagement<El extends OElement> {
 				oDatabaseDocument.commit();
 			}else {
 				 if(operationValidator==null) {
-					 throw new ResourceRegistryException("A removeFromContext operation which must not honour PropagationConstraints have to provide an " + OperationValidator.class.getSimpleName());
+					 throw new ResourceRegistryException("AddFromContext operation which must not honour PropagationConstraints have to provide an " + OperationValidator.class.getSimpleName());
 				 }
 				 if(operationValidator.isValidOperation(affectedInstances)) {
 					 oDatabaseDocument.commit();
@@ -845,7 +845,7 @@ public abstract class ElementManagement<El extends OElement> {
 				oDatabaseDocument.commit();
 			}else {
 				 if(operationValidator==null) {
-					 throw new ResourceRegistryException("A removeFromContext operation which must not honour PropagationConstraints have to provide an " + OperationValidator.class.getSimpleName());
+					 throw new ResourceRegistryException("RemoveFromContext operation which must not honour PropagationConstraints have to provide an " + OperationValidator.class.getSimpleName());
 				 }
 				 if(operationValidator.isValidOperation(affectedInstances)) {
 					 oDatabaseDocument.commit();
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/SharingOperationValidator.java b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/SharingOperationValidator.java
index 3beea67..b59fd8a 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/SharingOperationValidator.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/instances/model/SharingOperationValidator.java
@@ -8,6 +8,7 @@ import java.util.UUID;
 import org.gcube.com.fasterxml.jackson.databind.JsonNode;
 import org.gcube.informationsystem.base.reference.Element;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
+import org.gcube.informationsystem.resourceregistry.api.rest.SharingPath.SharingOperation;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -15,24 +16,24 @@ public class SharingOperationValidator implements OperationValidator {
 
 	protected static Logger logger = LoggerFactory.getLogger(SharingOperationValidator.class);
 	
-	protected final Map<UUID, JsonNode> expectedInstaces;
-	protected final String operation;
+	protected final Map<UUID, JsonNode> expectedInstances;
+	protected final SharingOperation sharingOperation;
 	
-	public SharingOperationValidator(Map<UUID, JsonNode> expectedInstaces, String operation) {
-		this.expectedInstaces = expectedInstaces;
-		this.operation = operation;
+	public SharingOperationValidator(Map<UUID, JsonNode> expectedInstances, SharingOperation sharingOperation) {
+		this.expectedInstances = expectedInstances;
+		this.sharingOperation = sharingOperation;
 	}
 	
 	@Override
 	public boolean isValidOperation(Map<UUID, JsonNode> affectedInstances) throws ResourceRegistryException {
-		Set<UUID> expectedUUIDSet = expectedInstaces.keySet();
+		Set<UUID> expectedUUIDSet = expectedInstances.keySet();
 		Set<UUID> affectedUUIDSet = new HashSet<>(affectedInstances.keySet());
 		
 		affectedUUIDSet.removeAll(expectedUUIDSet);
 		if(affectedUUIDSet.size()>0) {
 			StringBuffer stringBuffer = new StringBuffer();
 			stringBuffer.append("To keep the integrity of the IS the operation ");
-			stringBuffer.append(operation);
+			stringBuffer.append(sharingOperation.toString());
 			stringBuffer.append(" affects more instances than the requested by the client. The operation will be aborted. ");
 			stringBuffer.append("Additional affected instances are ");
 			stringBuffer.append(affectedUUIDSet.toString());
@@ -42,12 +43,12 @@ public class SharingOperationValidator implements OperationValidator {
 		}
 				
 		for(UUID expectedUUID : expectedUUIDSet) {
-			JsonNode expectedJsonNode = expectedInstaces.get(expectedUUID);
+			JsonNode expectedJsonNode = expectedInstances.get(expectedUUID);
 			JsonNode affectedJsonNode = affectedInstances.get(expectedUUID);
 			if(affectedJsonNode==null) {
 				StringBuffer stringBuffer = new StringBuffer();
 				stringBuffer.append("The operation ");
-				stringBuffer.append(operation);
+				stringBuffer.append(sharingOperation.toString());
 				stringBuffer.append(" did not affected the instance with UUID ");
 				stringBuffer.append(expectedUUID.toString());
 				stringBuffer.append(" ");
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/SharingManager.java b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/SharingManager.java
index c34e34f..ae28e4d 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/rest/SharingManager.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/rest/SharingManager.java
@@ -26,6 +26,7 @@ import org.gcube.informationsystem.resourceregistry.api.rest.SharingPath;
 import org.gcube.informationsystem.resourceregistry.api.rest.SharingPath.SharingOperation;
 import org.gcube.informationsystem.resourceregistry.instances.base.ElementManagement;
 import org.gcube.informationsystem.resourceregistry.instances.base.ElementManagementUtility;
+import org.gcube.informationsystem.resourceregistry.instances.model.SharingOperationValidator;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -127,7 +128,8 @@ public class SharingManager {
 			elementManagement.setHonourPropagationConstraintsInContextSharing(false);
 			elementManagement.setDryRunContextSharing(dryRun);
 			UUID contextUUID = UUID.fromString(contextId);
-			Map<UUID,JsonNode> affectedInstances = elementManagement.addToContext(contextUUID);
+			SharingOperationValidator sharingOperationValidator = new SharingOperationValidator(expectedInstances, operation);
+			Map<UUID,JsonNode> affectedInstances = elementManagement.addToContext(contextUUID, sharingOperationValidator);
 			
 			return serializeAffectedInstaces(objectMapper, affectedInstances);
 		}catch (ResourceRegistryException e) {