Notes

We faced a very strange behaviour with Citrix ADC (NetScaler). We use two NetScaler VMs to load balance two Citrix StoreFront servers. The StoreFront is SSL / TLS secured.

They suddenly stopped serving to serve the StoreFront web site, but without any explanation. Every status sign in NetScaler was green, the SSL certificate was not expired and since we use the freemium version, there was no license that could expire. The HTTP and HTTPS ports were open (tested using Test-NetConnection) and even the HTTP to HTTPS redirect worked. But the StoreFront page did not show up. Also the NetScaler log did not show that there was any config change or any other problem.

We tried to failover the NetScalers, to reboot them and to restore an older config file. But none of these measures did work. We also considered some NetScaler experts, but like us, they had no idea what was wrong.

The last idea we had was to restore the last night's backup of the VMs. Whatever the problem was, restoring the backup solved it. We really had no idea what the problem was, it didn't reoccur the last few days.