diff --git a/db/routines/vn/procedures/expeditionPallet_build.sql b/db/routines/vn/procedures/expeditionPallet_build.sql
index 2df73bb85..a33439061 100644
--- a/db/routines/vn/procedures/expeditionPallet_build.sql
+++ b/db/routines/vn/procedures/expeditionPallet_build.sql
@@ -5,22 +5,26 @@ CREATE OR REPLACE DEFINER=`vn`@`localhost` PROCEDURE `vn`.`expeditionPallet_buil
 	vWorkerFk INT,
 	OUT vPalletFk INT
 )
-BEGIN
-/** Construye un pallet de expediciones.
+proc: BEGIN
+/** 
+ * Builds an expedition pallet.
  *
- * Primero comprueba si esas expediciones ya pertenecen a otro pallet,
- * en cuyo caso actualiza ese pallet.
+ * First, it checks if these expeditions already belong to another pallet,
+ * in which case it returns an error.
  *
- * @param vExpeditions JSON_ARRAY con esta estructura [exp1, exp2, exp3, ...]
- * @param vArcId INT Identificador de arcRead
- * @param vWorkerFk INT Identificador de worker
- * @param out vPalletFk Identificador de expeditionPallet
+ * @param vExpeditions JSON_ARRAY with this structure [exp1, exp2, exp3, ...]
+ * @param vArcId INT Identifier of arcRead
+ * @param vWorkerFk INT Identifier of worker
+ * @param out vPalletFk Identifier of expeditionPallet
  */
+
 	DECLARE vCounter INT;
 	DECLARE vExpeditionFk INT;
 	DECLARE vTruckFk INT;
 	DECLARE vPrinterFk INT;
 	DECLARE vExpeditionStateTypeFk INT;
+	DECLARE vFreeExpeditionCount INT;
+	DECLARE vExpeditionWithPallet INT;
 
 	CREATE OR REPLACE TEMPORARY TABLE tExpedition (
 		expeditionFk INT,
@@ -44,48 +48,63 @@ BEGIN
 				WHERE e.id = vExpeditionFk;
 	END WHILE;
 
-	SELECT palletFk INTO vPalletFk
-		FROM (
-			SELECT palletFk, count(*) n
-				FROM tExpedition
-					WHERE palletFk > 0
-				GROUP BY palletFk
-				ORDER BY n DESC
-				LIMIT 100 
-		) sub
-		LIMIT 1;
+	SELECT COUNT(expeditionFk) INTO vFreeExpeditionCount 
+		FROM tExpedition 
+		WHERE palletFk IS NULL;
 
-	IF vPalletFk IS NULL THEN
-		SELECT roadmapStopFk INTO vTruckFk
-			FROM (
-				SELECT rm.roadmapStopFk, count(*) n
-					FROM routesMonitor rm
-						JOIN tExpedition e ON e.routeFk = rm.routeFk
-					GROUP BY roadmapStopFk
-					ORDER BY n DESC
-					LIMIT 1
-			) sub;
+	SELECT COUNT(expeditionFk) INTO vExpeditionWithPallet
+		FROM tExpedition 
+		WHERE palletFk;
 
-		IF vTruckFk IS NULL THEN
-				CALL util.throw ('TRUCK_NOT_AVAILABLE');
-		END IF;
-
-		INSERT INTO expeditionPallet SET truckFk = vTruckFk;
-
-		SET vPalletFk = LAST_INSERT_ID();
+	IF vExpeditionWithPallet THEN
+		UPDATE arcRead 
+			SET error = (
+				SELECT GROUP_CONCAT(expeditionFk SEPARATOR ', ')
+					FROM tExpedition 
+					WHERE palletFk
+			)
+		WHERE id = vArcId;
+		LEAVE proc;
 	END IF;
 
+	IF NOT vFreeExpeditionCount THEN
+		CALL util.throw ('NO_FREE_EXPEDITIONS');
+	END IF;
+
+	SELECT roadmapStopFk INTO vTruckFk
+		FROM (
+			SELECT rm.roadmapStopFk, count(*) n
+				FROM routesMonitor rm
+					JOIN tExpedition e ON e.routeFk = rm.routeFk
+				WHERE e.palletFk IS NULL
+				GROUP BY roadmapStopFk
+				ORDER BY n DESC
+				LIMIT 1
+		) sub;
+
+	IF vTruckFk IS NULL THEN
+		CALL util.throw ('TRUCK_NOT_AVAILABLE');
+	END IF;
+
+	INSERT INTO expeditionPallet SET truckFk = vTruckFk;
+
+	SET vPalletFk = LAST_INSERT_ID();
+
 	INSERT INTO expeditionScan(expeditionFk, palletFk, workerFk)
 		SELECT expeditionFk, vPalletFk, vWorkerFk
 			FROM tExpedition
-			ON DUPLICATE KEY UPDATE palletFk = vPalletFk, workerFk = vWorkerFk;
+			WHERE palletFk IS NULL;
 
 	SELECT id INTO vExpeditionStateTypeFk
 		FROM expeditionStateType
 		WHERE code = 'PALLETIZED';
-
+	
 	INSERT INTO expeditionState(expeditionFk, typeFk)
-		SELECT expeditionFk, vExpeditionStateTypeFk FROM tExpedition;
+		SELECT expeditionFk, vExpeditionStateTypeFk 
+			FROM tExpedition
+			WHERE palletFk IS NULL;
+
+	UPDATE arcRead SET error = NULL WHERE id = vArcId;
 
 	SELECT printerFk INTO vPrinterFk FROM arcRead WHERE id = vArcId;