Error: Cannot connect to the Citrix server. Protocol Driver ErrorThis morning I got reports form my Service Desk that users were receiving a protocol driver error.
The environment is a Presentation Server 4 environment with four servers. After completing all my basic troubleshooting, I tried telnet'ing to my servers over ICA, and noticed two of my servers (CTX01 and CTX02) were not accepting connections on port 1494 (You can test to see if ICA is opened from a windows machine, by using "netstat -ano | findstr "1494""). Also, multiple restarts of the servers did not help the situation.
Before trying to recreate the ICA listener to get ICA opened up and working, I decided to try something different. I disabled and then re-enabled the ICA listener on the two servers and "Wa-Lah"! It Worked! This option is so much easier than having to delete and recreate the ICA Listener and all the security settings attached to it.
Below are some additional things you may try if you receive the protocol driver error message and disabling and re-enabling the ICA Listener doesn't work.
- Disable Windows Firewall
- Make sure you can RDP to each of your Citrix Servers
- Disable Session Reliability, test, and then re-enable Session Reliability