Citrix SSLVPN client not connecting on Win 7 machines after upgrading to 11.1 release. But it works fine when trying to connect from Win 8 and 10 machines.

On Win 7 machines user might see the "Upgrade plug-in" prompt coming repeatedly as shown below or after authenticating, users will be redirected back to the logon page.



 

Issue will be fixed if you upgrade NetScaler to 11.1-49.x builds and also install the patch KB3033929 on the Windows 7 client.

Incase if the issue still persists despite of installing the patch, please perform the following:

1) After installing the patch,reboot the client machine and check.
2) If the issue persists, uninstall the VPN plugin, reboot the machine and re-install it and check

From the client side VPN debug logs, we see below difference when we tested from Windows 7 machine (Non-working) and Windows 8 machine (Working):

Win 7 logs:
===
16:49:43.484 | DEBUG   | ns_check_ndisdriverversion called
16:49:43.484 | ERROR   | ns_check_ndisdriverversion | 161 | CTXVPN: failed to start open driver handle when clearing driver filter.
16:49:43.484 | DEBUG   | ns_check_ndisdriverversion returned 0.
16:49:43.484 | EVENT   | The correct version of the NDIS driver is not installed.
16:49:43.484 | DEBUG   | Correct version of NDIS is not installed
16:49:43.485 | DEBUG   | ns_stop_vpn_prelogout() called
 
Win 8 logs:
===
 
16:36:31.163 | DEBUG   | ns_check_ndisdriverversion called
16:36:31.163 | DEBUG   | ns_check_ndisdriverversion: returns 1.1.0.255, requires 1.1.0.255
16:36:31.163 | DEBUG   | ns_check_ndisdriverversion returned 2.
16:36:31.163 | DEBUG   | Setting NDIS driver key...
16:36:31.167 | VERBOSE | Client will support 256 tunneled connections
16:36:31.168 | DEBUG   | Succeeded in setting HKCU\Software\Microsoft\Internet Explorer\Main\AllowWindowReuse
 

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Problem Cause

The issue is caused due to nsload.exe component of VPN signed by SHA2 from 11.1 onwards which is not supported by Win7 RTM unless customer's have installed security patch KB3033929 on that user's Windows machine.

This article talks about the issue where users will complain of not been able to connect to Citrix VPN plugin only from Win 7 machines. But works when using Win 8 or Win 10 machines.

https://support.microsoft.com/en-us/kb/3033929