I had created one site collection under web application using same site template. I have two master pages one for admin level one for read level permission users.
Everything was working fine with top level site.But in site collection all the popups are not opening. I see a "File not found error".
I checked with logfile using this id.I found below errors.
Application error when access /_layouts/15/Test.aspx,
Error=The file /_catalogs/masterpage/User.master does not exist.
Claims Windows Sign-In: Sending 401 for request 'url of the site' because the user is not authenticated and resource requires authentication.
How to resolve this issue ? can you please someone help me on this.