diff --git a/src/components/VehiclesManager/VehicleGroupEditModal.vue b/src/components/VehiclesManager/VehicleGroupEditModal.vue
index c3ede1f..2fb2cc8 100644
--- a/src/components/VehiclesManager/VehicleGroupEditModal.vue
+++ b/src/components/VehiclesManager/VehicleGroupEditModal.vue
@@ -71,6 +71,7 @@
         <div class="details-cargo-types" v-if="currentVehicleGroupType == 'wagon'">
           <input type="checkbox" id="include-cargo-types" v-model="includeCargoTypes" />
           <label for="include-cargo-types">Ładunki (wagon):</label>
+          (JSON: {{ isCargoTypesJsonValid ? 'poprawny' : 'niepoprawny' }})
           <br />
           <textarea name="cargo-types-textarea" id="cargo-types-textarea" v-model="cargoTypesJsonString">{{
             JSON.stringify(vehicleGroupValues.cargoTypes)
@@ -161,6 +162,8 @@ onMounted(() => {
   modalElementRef.value?.focus();
 });
 
+// JSON watchers
+
 watch(massSpeedsJsonString, (val) => {
   try {
     JSON.parse(val);
@@ -170,6 +173,15 @@ watch(massSpeedsJsonString, (val) => {
   }
 });
 
+watch(cargoTypesJsonString, (val) => {
+  try {
+    JSON.parse(val);
+    isCargoTypesJsonValid.value = true;
+  } catch (error) {
+    isCargoTypesJsonValid.value = false;
+  }
+});
+
 function populateVehicleGroupValues(vehicleGroup: IVehicleGroup) {
   if (!vehicleGroup.locoProps) currentVehicleGroupType.value = 'wagon';
 
@@ -228,6 +240,16 @@ async function updateVehicleGroup() {
 
   if (!vehicleGroup) return;
 
+  if (!isMassSpeedsJsonValid.value) {
+    alert('JSON dopuszczalnych mas jest niepoprawny! Popraw go przed zaktualizowaniem danych!');
+    return;
+  }
+
+  if (!isCargoTypesJsonValid.value) {
+    alert('JSON ładunków jest niepoprawny! Popraw go przed zaktualizowaniem danych!');
+    return;
+  }
+
   try {
     const updatedData = (
       await client.put<UpdateVehicleGroupAPIResponse>(`/manager/vehicleGroups/${vehicleGroup.id}`, {
@@ -249,7 +271,7 @@ async function updateVehicleGroup() {
       tableObject.vehicleGroupRef = updatedData;
     }
 
-    // alert('Zaktualizowano grupę: ' + updatedData.name);
+    alert('Zaktualizowano grupę: ' + updatedData.name);
     closeModal();
   } catch (error) {
     alert(handleAPIErrors(error));
@@ -274,7 +296,7 @@ async function removeVehicleGroup() {
       (v) => v.vehicleGroupRef.id != vehicleGroup.id,
     );
 
-    // alert('Usunięto pojazd: ' + removedData.name);
+    alert('Usunięto pojazd: ' + removedData.name);
     closeModal();
   } catch (error) {
     alert(handleAPIErrors(error));