diff --git a/src/openforms/js/components/admin/form_design/registrations/objectsapi/ObjectsApiOptionsFormFields.js b/src/openforms/js/components/admin/form_design/registrations/objectsapi/ObjectsApiOptionsFormFields.js
index b43f360be5..8bd06a26bb 100644
--- a/src/openforms/js/components/admin/form_design/registrations/objectsapi/ObjectsApiOptionsFormFields.js
+++ b/src/openforms/js/components/admin/form_design/registrations/objectsapi/ObjectsApiOptionsFormFields.js
@@ -40,6 +40,14 @@ const ObjectsApiOptionsFormFields = ({index, name, schema, formData, onChange})
   const [availableObjecttypes, setAvailableObjecttypes] = useState([]);
   const [availableObjecttypeVersions, setAvailableObjecttypeVersions] = useState([]);
 
+  const v2SwitchMessage = intl.formatMessage({
+    defaultMessage: `Switching to the new registration options will remove the existing JSON templates.
+    You will also not be able to save the form until the variables are correctly mapped.
+    Are you sure you want to continue?
+    `,
+    description: 'V2 Switch warning message',
+  });
+
   const {
     version = 1,
     objecttype = '',
@@ -55,14 +63,20 @@ const ObjectsApiOptionsFormFields = ({index, name, schema, formData, onChange})
   } = formData;
 
   const changeVersion = index => {
+    if (index === 1) {
+      const confirmV2Switch = window.confirm(v2SwitchMessage);
+      if (!confirmV2Switch) return;
+    }
+
     onChange(
       produce(formData, draft => {
+        draft.objecttype = '';
+        draft.objecttypeVersion = '';
+        draft.contentJson = '';
+        draft.paymentStatusUpdateJson = '';
         draft.version = index + 1;
       })
     );
-    if (version === 2) {
-      // open modal
-    }
   };
 
   const onFieldChange = event => {
@@ -114,7 +128,7 @@ const ObjectsApiOptionsFormFields = ({index, name, schema, formData, onChange})
 
   return (
     <>
-      <Tabs onSelect={changeVersion}>
+      <Tabs selectedIndex={version - 1} onSelect={changeVersion}>
         <TabList>
           <Tab>
             <FormattedMessage