Authenticate ajax multicast request before starting file upload

I am uploading files to Java Servlet via ajax. I need to authenticate the download request before starting the download.

I added my authentication token before sending the request like (AJAX)

beforeSend: function(request) { request.setRequestHeader("tokenName", "tokenData");
},

      

        
        
        
      

    

and got it in a servlet filter like

String tokenData=httpRequest.getHeader("tokenName");

      

        
        
        
      

    

This works fine until the token is valid. Now when I upload a large file, say 512MB, the browser starts uploading and before it finishes uploading, I already check the authentication token on the servlet side and if it is not a valid token I return a JSON ERROR, resulting in net :: ERR_CONNECTION_RESET is on CHROME and does not display the JSON response I sent.

How can I avoid net :: ERR_CONNECTION_RESET or check the token before starting the download.