diff --git a/src/ajax.js b/src/ajax.js
index 55250494a..f12b231a8 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -258,7 +258,8 @@ jQuery.extend({
 
 		responseFields: {
 			xml: "responseXML",
-			text: "responseText"
+			text: "responseText",
+			json: "responseJSON"
 		},
 
 		// Data converters
@@ -604,13 +605,19 @@ jQuery.extend({
 			// Set readyState
 			jqXHR.readyState = status > 0 ? 4 : 0;
 
+			// Determine if successful
+			isSuccess = status >= 200 && status < 300 || status === 304;
+
 			// Get response data
 			if ( responses ) {
 				response = ajaxHandleResponses( s, jqXHR, responses );
 			}
 
+			// Convert no matter what (that way responseXXX fields are always set)
+			response = ajaxConvert( s, response, jqXHR, isSuccess );
+
 			// If successful, handle type chaining
-			if ( status >= 200 && status < 300 || status === 304 ) {
+			if ( isSuccess ) {
 
 				// Set the If-Modified-Since and/or If-None-Match header, if in ifModified mode.
 				if ( s.ifModified ) {
@@ -626,20 +633,17 @@ jQuery.extend({
 
 				// 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, let's convert it
 				} else {
-					isSuccess = ajaxConvert( s, response );
-					statusText = isSuccess.state;
-					success = isSuccess.data;
-					error = isSuccess.error;
+					statusText = response.state;
+					success = response.data;
+					error = response.error;
 					isSuccess = !error;
 				}
 			} else {
@@ -699,7 +703,6 @@ jQuery.extend({
 });
 
 /* Handles responses to an ajax request:
- * - sets all responseXXX fields accordingly
  * - finds the right dataType (mediates between content-type and expected dataType)
  * - returns the corresponding response
  */
@@ -707,15 +710,7 @@ function ajaxHandleResponses( s, jqXHR, responses ) {
 
 	var ct, type, finalDataType, firstDataType,
 		contents = s.contents,
-		dataTypes = s.dataTypes,
-		responseFields = s.responseFields;
-
-	// Fill responseXXX fields
-	for ( type in responseFields ) {
-		if ( type in responses ) {
-			jqXHR[ responseFields[type] ] = responses[ type ];
-		}
-	}
+		dataTypes = s.dataTypes;
 
 	// Remove auto dataType and get content-type in the process
 	while( dataTypes[ 0 ] === "*" ) {
@@ -764,20 +759,14 @@ function ajaxHandleResponses( s, jqXHR, responses ) {
 	}
 }
 
-// Chain conversions given the request and the original response
-function ajaxConvert( s, response ) {
-
-	var conv, conv2, current, tmp,
+/* Chain conversions given the request and the original response
+ * Also sets the responseXXX fields on the jqXHR instance
+ */
+function ajaxConvert( s, response, jqXHR, isSuccess ) {
+	var conv2, current, conv, tmp, prev,
 		converters = {},
-		i = 0,
 		// Work with a copy of dataTypes in case we need to modify it for conversion
-		dataTypes = s.dataTypes.slice(),
-		prev = dataTypes[ 0 ];
-
-	// Apply the dataFilter if provided
-	if ( s.dataFilter ) {
-		response = s.dataFilter( response, s.dataType );
-	}
+		dataTypes = s.dataTypes.slice();
 
 	// Create converters map with lowercased keys
 	if ( dataTypes[ 1 ] ) {
@@ -786,14 +775,32 @@ function ajaxConvert( s, response ) {
 		}
 	}
 
-	// Convert to each sequential dataType, tolerating list modification
-	for ( ; (current = dataTypes[++i]); ) {
+	current = dataTypes.shift();
+
+	// Convert to each sequential dataType
+	while ( current ) {
+
+		if ( s.responseFields[ current ] ) {
+			jqXHR[ s.responseFields[ current ] ] = response;
+		}
+
+		// Apply the dataFilter if provided
+		if ( !prev && isSuccess && s.dataFilter ) {
+			response = s.dataFilter( response, s.dataType );
+		}
+
+		prev = current;
+		current = dataTypes.shift();
+
+		if ( current ) {
 
 		// There's only work to do if current dataType is non-auto
-		if ( current !== "*" ) {
+			if ( current === "*" ) {
+
+				current = prev;
 
 			// Convert response if prev dataType is non-auto and differs from current
-			if ( prev !== "*" && prev !== current ) {
+			} else if ( prev !== "*" && prev !== current ) {
 
 				// Seek a direct converter
 				conv = converters[ prev + " " + current ] || converters[ "* " + current ];
@@ -803,7 +810,7 @@ function ajaxConvert( s, response ) {
 					for ( conv2 in converters ) {
 
 						// If conv2 outputs current
-						tmp = conv2.split(" ");
+						tmp = conv2.split( " " );
 						if ( tmp[ 1 ] === current ) {
 
 							// If prev can be converted to accepted input
@@ -817,9 +824,8 @@ function ajaxConvert( s, response ) {
 								// Otherwise, insert the intermediate dataType
 								} else if ( converters[ conv2 ] !== true ) {
 									current = tmp[ 0 ];
-									dataTypes.splice( i--, 0, current );
+									dataTypes.unshift( tmp[ 1 ] );
 								}
-
 								break;
 							}
 						}
@@ -830,7 +836,7 @@ function ajaxConvert( s, response ) {
 				if ( conv !== true ) {
 
 					// Unless errors are allowed to bubble, catch and return them
-					if ( conv && s["throws"] ) {
+					if ( conv && s[ "throws" ] ) {
 						response = conv( response );
 					} else {
 						try {
@@ -841,9 +847,6 @@ function ajaxConvert( s, response ) {
 					}
 				}
 			}
-
-			// Update prev for next iteration
-			prev = current;
 		}
 	}
 
diff --git a/test/data/errorWithJSON.php b/test/data/errorWithJSON.php
new file mode 100644
index 000000000..62b187ecc
--- /dev/null
+++ b/test/data/errorWithJSON.php
@@ -0,0 +1,6 @@
+<?php
+
+header("HTTP/1.0 400 Bad Request");
+header("Content-Type: application/json");
+
+echo '{ "code": 40, "message": "Bad Request" }';
\ No newline at end of file
diff --git a/test/unit/ajax.js b/test/unit/ajax.js
index e5e82f977..e2335e507 100644
--- a/test/unit/ajax.js
+++ b/test/unit/ajax.js
@@ -1378,6 +1378,18 @@ module( "ajax", {
 
 	});
 
+	ajaxTest( "#11151 - jQuery.ajax() - parse error body", 2, {
+		url: url("data/errorWithJSON.php"),
+		dataFilter: function( string ) {
+			ok( false, "dataFilter called" );
+			return string;
+		},
+		error: function( jqXHR ) {
+			strictEqual( jqXHR.responseText, "{ \"code\": 40, \"message\": \"Bad Request\" }", "Error body properly set" );
+			deepEqual( jqXHR.responseJSON, { code: 40, message: "Bad Request" }, "Error body properly parsed" );
+		}
+	});
+
 	ajaxTest( "#11426 - jQuery.ajax() - loading binary data shouldn't throw an exception in IE", 1, {
 		url: url("data/1x1.jpg"),
 		success: function( data ) {
@@ -1477,6 +1489,16 @@ module( "ajax", {
 		}
 	});
 
+	ajaxTest( "#13388 - jQuery.ajax() - responseXML", 3, {
+		url: url("data/with_fries.xml"),
+		dataType: "xml",
+		success: function( resp, _, jqXHR ) {
+			notStrictEqual( resp, undefined, "XML document exists" );
+			ok( "responseXML" in jqXHR, "jqXHR.responseXML exists" );
+			strictEqual( resp, jqXHR.responseXML, "jqXHR.responseXML is set correctly" );
+		}
+	});
+
 //----------- jQuery.ajaxPrefilter()
 
 	ajaxTest( "jQuery.ajaxPrefilter() - abort", 1, {