diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index d599799..041550d 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -71,6 +71,55 @@ Drupal.behaviors.AJAX = {
 };
 
 /**
+ * Build an error message from an Ajax response.
+ */
+Drupal.ajaxError = function (xmlhttp, uri) {
+  console.error(Drupal.t("An AJAX HTTP error occurred."), uri, xmlhttp);
+
+  // Return an object we can print as a string This avoid processing the several
+  // try/catch when there is no need to.
+  return {
+    uri: uri,
+    xmlhttp: xmlhttp,
+    toString: function () {
+      var statusCode, statusText, pathText, responseText, readyStateText, message;
+      if (xmlhttp.status) {
+        statusCode = "\n" + Drupal.t("An AJAX HTTP error occurred.") + "\n" + Drupal.t("HTTP Result Code: !status", {'!status': xmlhttp.status});
+      }
+      else {
+        statusCode = "\n" + Drupal.t("An AJAX HTTP request terminated abnormally.");
+      }
+      statusCode += "\n" + Drupal.t("Debugging information follows.");
+      pathText = "\n" + Drupal.t("Path: !uri", {'!uri': uri} );
+      statusText = '';
+      // In some cases, when statusCode == 0, xmlhttp.statusText may not be defined.
+      // Unfortunately, testing for it with typeof, etc, doesn't seem to catch that
+      // and the test causes an exception. So we need to catch the exception here.
+      try {
+        statusText = "\n" + Drupal.t("StatusText: !statusText", {'!statusText': $.trim(xmlhttp.statusText)});
+      }
+      catch (e) {}
+
+      responseText = '';
+      // Again, we don't have a way to know for sure whether accessing
+      // xmlhttp.responseText is going to throw an exception. So we'll catch it.
+      try {
+        responseText = "\n" + Drupal.t("ResponseText: !responseText", {'!responseText': $.trim(xmlhttp.responseText) } );
+      } catch (e) {}
+
+      // Make the responseText more readable by stripping HTML tags and newlines.
+      responseText = responseText.replace(/<("[^"]*"|'[^']*'|[^'">])*>/gi,"");
+      responseText = responseText.replace(/[\n]+\s+/g,"\n");
+
+      // We don't need readyState except for status == 0.
+      readyStateText = xmlhttp.status == 0 ? ("\n" + Drupal.t("ReadyState: !readyState", {'!readyState': xmlhttp.readyState})) : "";
+
+      return statusCode + pathText + statusText + responseText + readyStateText;
+    }
+  };
+};
+
+/**
  * Ajax object.
  *
  * All Ajax objects on a page are accessible through the global Drupal.ajax
@@ -252,7 +301,7 @@ Drupal.ajax.prototype.eventResponse = function (element, event) {
     // Unset the ajax.ajaxing flag here because it won't be unset during
     // the complete response.
     ajax.ajaxing = false;
-    alert("An error occurred while attempting to process " + ajax.options.url + ": " + e.message);
+    console.error("An error occurred while attempting to process " + ajax.options.url, e.message, ajax, e);
   }
 
   // For radio/checkbox, allow the default event. On IE, this means letting
@@ -441,7 +490,7 @@ Drupal.ajax.prototype.getEffect = function (response) {
  * Handler for the form redirection error.
  */
 Drupal.ajax.prototype.error = function (response, uri) {
-  alert(Drupal.ajaxError(response, uri));
+  Drupal.ajaxError(response, uri);
   // Remove the progress element.
   if (this.progress.element) {
     $(this.progress.element).remove();
diff --git a/core/misc/autocomplete.js b/core/misc/autocomplete.js
index 8b0dd72..2fe6c9f 100644
--- a/core/misc/autocomplete.js
+++ b/core/misc/autocomplete.js
@@ -312,7 +312,7 @@ Drupal.ACDB.prototype.search = function (searchString) {
         }
       },
       error: function (xmlhttp) {
-        alert(Drupal.ajaxError(xmlhttp, db.uri));
+        Drupal.ajaxError(xmlhttp, db.uri);
       }
     });
   }, this.delay);
diff --git a/core/misc/drupal.js b/core/misc/drupal.js
index 75767d5..42d6689 100644
--- a/core/misc/drupal.js
+++ b/core/misc/drupal.js
@@ -5,7 +5,7 @@ jQuery.noConflict();
 
 // JavaScript should be made compatible with libraries other than jQuery by
 // wrapping it in an anonymous closure.
-(function ($, Drupal, window, document, undefined) {
+(function ($, Drupal, window, document, console, undefined) {
 
 "use strict";
 
@@ -112,6 +112,15 @@ Drupal.detachBehaviors = function (context, settings, trigger) {
   }
 };
 
+// Create dummy functions if browser console is not available.
+if (typeof console !== 'object') {
+  console = {
+    log: function () {},
+    warn: function () {},
+    error: function () {}
+  };
+}
+
 /**
  * Encode special characters in a plain-text string for display as HTML.
  *
@@ -338,46 +347,6 @@ Drupal.getSelection = function (element) {
   return { 'start': element.selectionStart, 'end': element.selectionEnd };
 };
 
-/**
- * Build an error message from an Ajax response.
- */
-Drupal.ajaxError = function (xmlhttp, uri) {
-  var statusCode, statusText, pathText, responseText, readyStateText, message;
-  if (xmlhttp.status) {
-    statusCode = "\n" + Drupal.t("An AJAX HTTP error occurred.") +  "\n" + Drupal.t("HTTP Result Code: !status", {'!status': xmlhttp.status});
-  }
-  else {
-    statusCode = "\n" + Drupal.t("An AJAX HTTP request terminated abnormally.");
-  }
-  statusCode += "\n" + Drupal.t("Debugging information follows.");
-  pathText = "\n" + Drupal.t("Path: !uri", {'!uri': uri} );
-  statusText = '';
-  // In some cases, when statusCode == 0, xmlhttp.statusText may not be defined.
-  // Unfortunately, testing for it with typeof, etc, doesn't seem to catch that
-  // and the test causes an exception. So we need to catch the exception here.
-  try {
-    statusText = "\n" + Drupal.t("StatusText: !statusText", {'!statusText': $.trim(xmlhttp.statusText)});
-  }
-  catch (e) {}
-
-  responseText = '';
-  // Again, we don't have a way to know for sure whether accessing
-  // xmlhttp.responseText is going to throw an exception. So we'll catch it.
-  try {
-    responseText = "\n" + Drupal.t("ResponseText: !responseText", {'!responseText': $.trim(xmlhttp.responseText) } );
-  } catch (e) {}
-
-  // Make the responseText more readable by stripping HTML tags and newlines.
-  responseText = responseText.replace(/<("[^"]*"|'[^']*'|[^'">])*>/gi,"");
-  responseText = responseText.replace(/[\n]+\s+/g,"\n");
-
-  // We don't need readyState except for status == 0.
-  readyStateText = xmlhttp.status == 0 ? ("\n" + Drupal.t("ReadyState: !readyState", {'!readyState': xmlhttp.readyState})) : "";
-
-  message = statusCode + pathText + statusText + responseText + readyStateText;
-  return message;
-};
-
 // Class indicating that JS is enabled; used for styling purpose.
 $('html').addClass('js');
 
@@ -407,4 +376,4 @@ Drupal.theme.prototype = {
   }
 };
 
-})(jQuery, Drupal, this, this.document);
+})(jQuery, Drupal, this, this.document, window['console']);
diff --git a/core/misc/progress.js b/core/misc/progress.js
index 343b9ad..086ae25 100644
--- a/core/misc/progress.js
+++ b/core/misc/progress.js
@@ -87,7 +87,8 @@ Drupal.progressBar.prototype.sendPing = function () {
         pb.timer = setTimeout(function () { pb.sendPing(); }, pb.delay);
       },
       error: function (xmlhttp) {
-        pb.displayError(Drupal.ajaxError(xmlhttp, pb.uri));
+        var error = Drupal.ajaxError(xmlhttp, pb.uri);
+        pb.displayError(error.toString());
       }
     });
   }