The below mentioned answer is correct. All you need to do is create a class and inherit res.partner model and Also check the view inheritance. if some other model has inherited the view of res.partner, you can check that by enabling debugging mode and click on debug menu and select edit view: form. There under the inherited views, you can see all the inherited views of res.partner. And another thing is sometimes when we create a field, it will not get loaded and shows field not found error when we try to upgrade from UI. To solve that you should upgrade from the configuration itself by passing parameter -u module name. Thank you.