Unsupported media type ASP.NET Core Web API

I had this where the receiving controller method was expecting a [FromBody] argument, but the calling service omitted the parameter. At a guess under the hood, a controller method that expects a (serialised) parameter would expect the request content type (MIME) to be application/json - but the HttpClient calling POST/PUT without a parameter does not pass this (maybe just text/html) - and hence we get 415 'Unsupported Media Type'.

This is a CORS issue.

During development it's safe to accept all http request methods from all origins. Add the following to your startup.cs:

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        loggerFactory.AddConsole(Configuration.GetSection("Logging"));
        loggerFactory.AddDebug();

        //Accept All HTTP Request Methods from all origins
        app.UseCors(builder =>
            builder.AllowAnyHeader().AllowAnyOrigin().AllowAnyMethod());

        app.UseMvc();
    }

See here for more details about CORS.

The header you are sending is wrong. You are sending Content-Type: application/json, but you have to send Accept: application/json.

Content-Type: application/json is what the server must send to the client and the client must send Accept to tell the server which type of response it accepts.

addNewSalesman: function (newData) {
        console.log("service");
        console.log(newData)
        var deferred = $q.defer();
        $http({
            method: 'POST',
            url: '/api/Salesman',
            headers: { 'Accept': 'application/json' }
        }, newData).then(function (res) {
            deferred.resolve(res.data);
        }, function (res) {
            deferred.reject(res);
        });
        return deferred.promise;
    }

Should do it. Also see "Content negotiation" on MDN.

Just replace [FromBody] to [FromForm] in your controller.