diff --git a/sigla-web/src/main/java/it/cnr/contab/util/servlet/JSONRequest.java b/sigla-web/src/main/java/it/cnr/contab/util/servlet/JSONRequest.java
index 7d6f771124..2f69ff5510 100644
--- a/sigla-web/src/main/java/it/cnr/contab/util/servlet/JSONRequest.java
+++ b/sigla-web/src/main/java/it/cnr/contab/util/servlet/JSONRequest.java
@@ -1,8 +1,10 @@
 package it.cnr.contab.util.servlet;
 
+import it.cnr.jada.comp.ComponentException;
 import it.cnr.jada.persistency.sql.SQLBuilder;
 
 import java.util.List;
+import java.util.Optional;
 
 public class JSONRequest extends JSONRESTRequest{
 	private Integer activePage;
@@ -115,6 +117,24 @@ else if (operator.equalsIgnoreCase("isnotnull"))
 				return SQLBuilder.ISNOTNULL;
 			return SQLBuilder.EQUALS;
 		}
+
+		@Override
+		public String toString() {
+			return "Clause {" +
+					"condition='" + condition + '\'' +
+					", fieldName='" + fieldName + '\'' +
+					", operator='" + operator + '\'' +
+					", fieldValue=" + fieldValue +
+					'}';
+		}
+
+		public void validate() throws ComponentException{
+			if (!Optional.ofNullable(getSQLOperator()).isPresent() || !Optional.ofNullable(getFieldName()).isPresent())
+				throw new ComponentException("Cannot add clause " + this);
+			if (!(getSQLOperator() == SQLBuilder.ISNULL || getSQLOperator() == SQLBuilder.ISNOTNULL) &&
+					!Optional.ofNullable(getFieldValue()).isPresent())
+				throw new ComponentException("Cannot add clause " + this);
+		}
 	}
 
 }
diff --git a/sigla-web/src/main/java/it/cnr/contab/util/servlet/RESTServlet.java b/sigla-web/src/main/java/it/cnr/contab/util/servlet/RESTServlet.java
index dfe55e01da..89e404d4bf 100644
--- a/sigla-web/src/main/java/it/cnr/contab/util/servlet/RESTServlet.java
+++ b/sigla-web/src/main/java/it/cnr/contab/util/servlet/RESTServlet.java
@@ -29,6 +29,7 @@
 import it.cnr.jada.comp.ApplicationException;
 import it.cnr.jada.comp.ComponentException;
 import it.cnr.jada.persistency.sql.CompoundFindClause;
+import it.cnr.jada.persistency.sql.SQLBuilder;
 import it.cnr.jada.util.OrderConstants;
 import it.cnr.jada.util.RemoteIterator;
 import it.cnr.jada.util.action.ConsultazioniBP;
@@ -141,7 +142,12 @@ protected void execute(HttpServletRequest req, HttpServletResponse resp, String
     		        			CompoundFindClause compoundFindClause = new CompoundFindClause();
     		        			for (Clause clause : jsonRequest.getClauses()) {
     		    	                logger.info("RequestedSessionId: "+req.getRequestedSessionId() + ". Clause. Condition: "+clause.getCondition()+", fieldName: "+clause.getFieldName()+", Operator: "+clause.getOperator()+", fieldValue: "+clause.getFieldValue());
-    		        				compoundFindClause.addClause(clause.getCondition(), clause.getFieldName(), clause.getSQLOperator(), clause.getFieldValue());
+                                    clause.validate();
+    		    	                compoundFindClause.addClause(
+                                            clause.getCondition(),
+                                            clause.getFieldName(),
+                                            clause.getSQLOperator(),
+                                            clause.getFieldValue());
     		        			}
     		        			consBP.setFindclause(compoundFindClause);
     		        		}