1. Go to Keychain Access and find the certificate that is a problem (for me it was Network Solutions Certificate Authority, but it could be any of a number of certificates).
2. Export the certificate to the desktop (right click/export) Ė it will appear as Network Solutions Certificate Authority.cer
3. Go to the Citrix folder on the Mac and look for a keystore/cacerts folder.
4. If the folder isnít there, you will need to create it. To do this, go to Applications/Citrix ICA Client. Create the folder keystore (Right click/new folder). Within that folder, create the folder cacerts. The path will be Applications/Citrix ICA Client/keystore/cacerts.
5. Copy the certificate exported from Keychain earlier (Network Solutions Certificate Authority.cer) to the Applications/Citrix ICA Client/keystore/cacerts folder. Some sources say you need to change the extension to .crt (so in the example, this would be Network Solutions Certificate Authority.crt), but that didnít work for me. The .cer extension did.
Now you should be able to access the VPN through its usual website on Firefox.