Without warning, Microsoft changed Internet Explorer’s User-Agent string.   As a result, some application owners got a big surprise when their applications suddenly lost the ability to identify IE browsers.   Some applications (Access Gateway Login pages included) broke!  Others, like SharePoint, assumed the unknown browser should receive the “mobile” version of its content and users didn’t get the full application experience.

Here’s a helpful way NetScaler can resolve the IE11 Compatibility problem.

With IE’s Compatibility View, websites will be displayed as if you were viewing them in a previous version of Internet Explorer, which will often correct display problems.  Fortunately, you don’t need to tell users to “click” on the Compatibility Mode button.  Instead, have NetScaler add explicit compatibility instructions, in real-time, to the content being sent to the browser:

<META http-equiv=”X-UA-Compatible” content=”IE=EmulateIE9″>


Use the following AppExpert rewrite action to add the IE compatibility instruction to the origin content.

add rewrite action NG-IE11 insert_after_all “HTTP.RES.BODY(6000)” q/”\r\n”+”<META http-equiv=\”X-UA-Compatible\” content=\”IE=EmulateIE9\”>”/ -search “text(\”</TITLE>\”)”

When repairing Access Gateway login pages, use the following policy and bind it as a Global Override:

add rewrite policy NG-IE11_rwpol “HTTP.REQ.URL.PATH.ENDSWITH(\”/vpn/index.html\”)” NG-IE11

bind rewrite global NG-IE11_rwpol 100 NEXT -type RES_OVERRIDE

With respect to NetScaler Gateway, versions 9.3.66.x and 10.1.123.x and onward will contain the necessary IE11 compatibility fix.  This resolves the case where IE11 bowsers receive a blank access gateway login page which has missing username and password form fields.


Compatibility View

Fixing the Citrix Access Gateway blank page in IE 11 (Internet Explorer 11) on your Netscaler

Internet Explorer 11’s Many User-Agent Strings

Best practices for NetScaler VPN Customizations