Client Detection Fail
This one is poorly documented, but I cannot be the only one it has happened to 🙂 We have 2 beautiful Citrix NetScaler MPX5500 devices in a HA config. Behind them we loadbalance 2 Citrix WebInterface 5.4 servers. When enabling just one of the WebInterfaces (doesn’t matter which one) ClientDetection works like a charm. When enabling both WI servers client detection fails. You get an error: “There was a problem with the client detection and the download process. Contact your system administrator”.
Nothing more frustration then getting an error that says contact your system administrator when you are the system administrator. Anyway, the problem described here is a persistency error. The vServer we use for loadbalancing our WebInterface servers has persistency enabled (Cookieinsert with backup SourceIP).
Default the Persistence Time-Out is set to 2 minutes, and that’s the problem. On the smaller NetScaler Devices or NetScaler VPX-es this can be an issue. Just increase this value. I set it to 1440, which means that when a user returns within 24 hours he will be redirected to the same WebInterface server. It doesn’t really matter, just make it (a lot) more then 2 minutes.
You can find this setting in your NetScaler Admin GUI > Load Balancing > Virtual Servers > Open your vServer > Tab Method and Persistence