Case
When trying to launch a Citrix Virtual App or Desktop you receive the following error message:
Error:”Cannot resolve the SSL Host name xxx.xxx.xxx (SSL error 40)”. An example occurrence of this error is shown in the screenshot below.
Solution
This issue’s root cause is the end-user DNS resolver (client) not working properly. In most of the cases the issue is resolved with the following actions:
- Clear your browser cache. Step-by-step instructions for all major browsers can be found at: https://kinsta.com/knowledgebase/how-to-clear-browser-cache/.
- Flush your DNS resolver. In Windows systems run the following command in an elevated Windows terminal: ipconfig /flushdns. In Debian-based Linux systems first check if DNS caching is enabled by running following command: ps ax | grep dnsmasq. If the cache-size parameter is not zero then the DNS cache needs to be flushed. Depending on your DNS service you will need to run the appropriate commands.
For Debian-based systems
sudo /etc/init.d/dns-clean restart
sudo /etc/init.d/networking force-reload
For nscd
sudo /etc/init.d/nscd restart
sudo /etc/init.d/dnsmasq restart
For BIND
sudo /etc/init.d/named restart
If issue persists despite the Web browser cache reset and DNS flush, you may also want to manually set your hosts file on the end-user machine, in case the DNS service is having issues.
You can find more detailed guidance and step-by-step procedures for analyzing and troubleshooting Citrix Virtual Apps and Desktops organized by category in my Citrix Virtual Apps and Desktops Troubleshooting e-book.
