The problem is that you mapped your servlet to /register.html
and it expects POST method, because you implemented only doPost()
method. So when you open register.html
page, it will not open html page with the form but servlet that handles the form data.
Alternatively when you submit POST form to non-existing URL, web container will display 405 error (method not allowed) instead of 404 (not found).
To fix:
<servlet-mapping>
<servlet-name>Register</servlet-name>
<url-pattern>/Register</url-pattern>
</servlet-mapping>