Request format is unrecognized for URL unexpectedly ending in

Found a solution on this website

All you need is to add the following to your web.config

<configuration>
  <system.web>
    <webServices>
      <protocols>
        <add name="HttpGet"/>
        <add name="HttpPost"/>
      </protocols>
    </webServices>
  </system.web>
</configuration>

More info from Microsoft

Despite 90% of all the information I found (while trying to find a solution to this error) telling me to add the HttpGet and HttpPost to the configuration, that did not work for me... and didn't make sense to me anyway.

My application is running on lots of servers (30+) and I've never had to add this configuration for any of them. Either the version of the application running under .NET 2.0 or .NET 4.0.

The solution for me was to re-register ASP.NET against IIS.

I used the following command line to achieve this...

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i

Make sure you're using right method: Post/Get, right content type and right parameters (data).

$.ajax({
    type: "POST",
    url: "/ajax.asmx/GetNews",
    data: "{Lang:'tr'}",
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (msg) { generateNews(msg); }
})

In my case the error happened when i move from my local PC Windows 10 to a dedicated server with Windows 2012. The solution for was to add to the web.config the following lines

<webServices>
        <protocols>
               <add name="Documentation"/>
        </protocols>
</webServices>

I did not have the issue when developing in localhost. However, once I published to a web server, the webservice was returning an empty (blank) result and I was seeing the error in my logs.

I fixed it by setting my ajax contentType to :

"application/json; charset=utf-8"

and using :

JSON.stringify()

on the object I was posting.

var postData = {data: myData};
$.ajax({
                type: "POST",
                url: "../MyService.asmx/MyMethod",
                data: JSON.stringify(postData), 
                contentType: "application/json; charset=utf-8",
                success: function (data) {
                    console.log(data);
                },
                dataType: "json"
            });

I was getting this error until I added (as shown in the code below) $.holdReady(true) at the beginning of my web service call and $.holdReady(false) after it ends. This is jQuery thing to suspend the ready state of the page so any script within document.ready function would be waiting for this (among other possible but unknown to me things).

<span class="AjaxPlaceHolder"></span>
<script type="text/javascript">
$.holdReady(true);
function GetHTML(source, section){
    var divToBeWorkedOn = ".AjaxPlaceHolder";
    var webMethod = "../MyService.asmx/MyMethod";
    var parameters = "{'source':'" + source + "','section':'" + section + "'}";

    $.ajax({
        type: "POST",
        url: webMethod,
        data: parameters,
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        async: true,
        xhrFields: {
            withCredentials: false
        },
        crossDomain: true,
        success: function(data) {
            $.holdReady(false);
            var myData = data.d;
            if (myData != null) {
                $(divToBeWorkedOn).prepend(myData.html);
            }
        },
        error: function(e){
            $.holdReady(false);
            $(divToBeWorkedOn).html("Unavailable");
        }
    });
}
GetHTML("external", "Staff Directory");
</script>