In this post I explain how I tried to troubleshoot this issue, if you need the solution, go at the end of this post. My company (Activlan) had to renew our certificate installed on our Citrix Secure Gateway 3.1.3. As you might know, Citrix has issued some virtual appliance and I had to chose between, Citrix Access Gateway 4.6.2 VPX and Netscaller VPX Express (Free !). My choice was to integrate a Citrix Access Gateway (CAG) mainly because we are using other product to manage VPN to all our customers and I wanted to install what I needed, nothing less, nothing more. So here we go, I got my xva file from MyCitrix account and I just deploy it on our XenServer, very easy, very simple, just some clicks. Once installed and basics configuration set, I had to generate the CSR (Certificate Signing Request) and wait for Verisign to send me the certificate I had to use with the CAG. This was a big adventure and of course I should have read the manual before, and configuration isn't so easy but I guess when you do it all day long you begin to know everything and I can say now, I know how to troubleshoot a CAG from the client side to the Web Interface. This error I got with my Mac didn't show up on my Windows computers. In fact Apple doesn't have a very big list of root certificate install on their OS compare to Windows. Here is the error message I got when I wanted to launch published application (XenApp). I was able to login in the CAG and the Web Interface as well, but not able to launch application. SSL Error 61: You have not chosen to trust "Verisign Class 3 Secure Server CA - G2", the issuer of the server's security certificate. Error number: 183 Sexy message, isn't it ? After searching around a bit I found this thread on Citrix's forums : http://forums.citrix.com/message.jspa?messageID=447656 everything went clear, I didn't had the root certificate on my computer to validate my brand new certificate from Verisign... So I tried to find how to get these root certificates, especially Verisign Class 3 Secure Server CA - G2, the one I needed. I found this Verisign address http://www.verisign.com/repository/roots/pca_certificate.html where you just have to fill a form to get a zip with everything what you might need : As you…