"The page you are looking for is missing. This could be because it is moved or there is a typo in the link." When triggers created web Hook

I have created a webhook to trigger the on_update event in my erpNext application.

URL - http://66.206.23.4/qo

content-type - x-form-url-encoded

Doc type - Quaotation

method - Post

But it is getting above error.

I have changed the url as https://demo1.techroot.lk/qo

Still it generates the same error.