Don't try and convert data for 204 No Content responses. Fixes #13292. Fixes #13261.

src/ajax.js

@@ -624,12 +624,17 @@ jQuery.extend({
 					}
 				}
 
-				// If not modified
-				if ( status === 304 ) {
+				// if no content
+				if ( status === 204 ) {
+					isSuccess = true;
+					statusText = "nocontent";
+
+				// if not modified
+				} else if ( status === 304 ) {
 					isSuccess = true;
 					statusText = "notmodified";
 
-				// If we have data
+				// If we have data, let's convert it
 				} else {
 					isSuccess = ajaxConvert( s, response );
 					statusText = isSuccess.state;

test/data/nocontent.php

+<?php
+
+header('HTTP/1.0 204 No Content');
+
+?>
\ No newline at end of file

test/unit/ajax.js

@@ -1498,6 +1498,26 @@ module( "ajax", {
 			strictEqual( ajaxXML.find("tab").length, 3, "Parsed node was added properly" );
 		}
 	});
+	
+	ajaxTest( "#13292 - jQuery.ajax() - converter is bypassed for 204 requests", 3, {
+		url: "data/nocontent.php",
+		dataType: "testing",
+		converters: {
+			"* testing": function() {
+				throw "converter was called";
+			}
+		},
+		success: function( data, status, jqXHR ) {
+			strictEqual( jqXHR.status, 204, "status code is 204" );
+			strictEqual( status, "nocontent", "status text is 'nocontent'" );
+			strictEqual( data, undefined, "data is undefined" );
+		},
+		error: function( _, status, error ) {
+			ok( false, "error" );
+			strictEqual( status, "parsererror", "Parser Error" );
+			strictEqual( error, "converter was called", "Converter was called" );
+		}
+	});
 
 //----------- jQuery.ajaxPrefilter()