diff --git a/liferay-plugins-sdk-6.2/portlets/portos-advanced-operation-portlet/docroot/WEB-INF/src/it/nextmind/liferay/portos/advanced/operation/util/AdvancedOperationUtil.java b/liferay-plugins-sdk-6.2/portlets/portos-advanced-operation-portlet/docroot/WEB-INF/src/it/nextmind/liferay/portos/advanced/operation/util/AdvancedOperationUtil.java
index ab8d1d0a..937c74fb 100644
--- a/liferay-plugins-sdk-6.2/portlets/portos-advanced-operation-portlet/docroot/WEB-INF/src/it/nextmind/liferay/portos/advanced/operation/util/AdvancedOperationUtil.java
+++ b/liferay-plugins-sdk-6.2/portlets/portos-advanced-operation-portlet/docroot/WEB-INF/src/it/nextmind/liferay/portos/advanced/operation/util/AdvancedOperationUtil.java
@@ -272,8 +272,10 @@ public class AdvancedOperationUtil {
 		if(Validator.isNotNull(lastTask)){
 			long assigneeUserId = lastTask.getAssigneeUserId();
 			try {
-				User assignee = UserLocalServiceUtil.getUser(assigneeUserId);
-				return UserUtil.getUnitaOperative(assignee);
+				if(-1 != assigneeUserId){
+					User assignee = UserLocalServiceUtil.getUser(assigneeUserId);
+					return UserUtil.getUnitaOperative(assignee);
+				}
 			} catch (SystemException | PortalException e){
 				_log.error("AOP ==> Error while analyzing IntPratica: " + intPratica.getIntPraticaId());
 				_log.error(e,e);