Custom form ajax submit data not working in magento 2.3 its working with magento 2.1 and 2.2.x versions.
Error 401 (Unauthorized)
Failed to load resource: the server responded with a status of 401 (Unauthorized)
Please give any suggestion
Please add form key to your post param.
form_key before process you action if it doesn't find form key in your form post data it will give authorization error or it may.
So it's highly recommended to add
form_key param with your post data to make it success.