Grunt Connect Proxy: 404 Not Found

not directly answering your question but providing a solution (since noone else has answered) ... have you tried the npm module connect-modrewrite

this does exactly what you are trying to do.

I was having the same issue i resolve this way and its work for me. Look into my code below:-

connect: {             server: {                 options: {                     keepalive: true,                     port: 8001,                     protocol: 'http',                     hostname: '*',                     directory: 'dist',                     open: {                         target: 'http://localhost:8001/myDemo.html',                     },                        middleware: function(connect, options, middlewares) {                                middlewares.unshift(function(req, res, next) {                                    res.setHeader('Access-Control-Allow-Credentials', true);                                    res.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");                                    res.setHeader('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');                                    **if (req.method.toUpperCase() == 'POST') req.method='GET';**                                    return next();                                });                                return middlewares;                        }                }             }         },

see the star marked line ie if (req.method.toUpperCase() == 'POST') req.method='GET'; i done this trick and its worked for me. This aricle also helps to me https://github.com/gruntjs/grunt-contrib-connect#middleware