phreek.org

I ran into an issue while upgrading components in preparation for our XenApp 5 migration where after installing Web Interface 5.2 I could connect and see my published applications but when I tried to launch one I would get an error “Citrix online plug-in could not contact the server”.

The solution is to edit the WebInterface.conf in your PN Agent IIS site and add a line “RequireLaunchReference=off”.

It took quite a bit of Googling but I found the solution.

The reason for this problem is that MS KB953230 uses the same range of ports as WDS defaults to (64001-65000) for TFTP file transfers so you need to set WDS to use a different port range (62000-63000 works well). This will only occur on a server where you have the DNS role installed as well as WDS (most likely a domain controller).