DeveloperExceptionPage not showing through Ajax Calls in .NetCore 2.2

You can get the exception information like this:

$.ajax({
            url: "@Url.Action("Index", "Home")",
            dataType: "json",
            type: "POST",
            Async: true,
            success: function (result) {
                // Do Something                  
            },
            error: function (result) {
                //do something with the responseText which contains the Body of the response
                alert(result.responseText);
            }
        });

The controller does NOT know if you called it using AJAX or not... It just looks at the Http Request. You can inspect the Http Response by adding a parameter to your error function.

For example you can inspect the responseText property to get the exception information.

You could for example set the contents to a div or other display element.

Also because your AJAX request's dataType is set to "json" the reponseText will contain only the exception information plus the headers.

If you set the dataType to "html" you will get the FULL Developer Exception Page's html which you can then do something with.

Here are a couple of examples on what to do with the responseText.

Example 1 when dataType: "html":

        $.ajax({
            url: "@Url.Action("Index", "Home")",
            dataType: "html",
            type: "POST",
            Async: true,
            success: function (result) {
                // Do Something                  
            },
            error: function (result) {
                document.open();
                document.write(result.responseText);//this will replace the current page with the developer exception page
                document.close();               
            }
        });

Example 2 when dataType: "json": This one is different because YOU requested JSON so the server does NOT return a full HTML Document.

This one does not look "pretty" but it has all the exception information.

$.ajax({
        url: "@Url.Action("Index", "Home")",
        dataType: "json",
        type: "POST",
        Async: true,
        success: function (result) {
            // Do Something                  
        },
        error: function (result) {
            document.body.innerHTML = result.responseText;                          
        }
    });