Updating this question as it is still relevant in later version of workspace app for Ubuntu/Debian x86_64, also adding a more specific solution.
This issue just happened to me after my company asked me to update from version 20 to 22, the local cert I was using before was lost during the manual package upgrade. here is what i did to re-trust the root CA my company is using.
Here is the error I got:
So from this error I can see Citrix does not trust the root CA certificate from the public cert company my own company is using, in this case «Entrust.com». I downloaded the root CA cert from their site, but as suggested in the Juan’s answer you could probably just copy all of Mozzilla trusted Certificates (I looked and the entrust root ca cert was in there).
Sadly Citrix does not seem to use the systems default cert store on linux builds. it expects to find the cert in it’s own local directory location; default for version 22 on ubuntu is: /opt/Citrix/ICAClient/keystore/cacerts.
Which is the cause of this error, if it used the default store it would not be an issue.
Copy the root CA cert you downloaded in there eg.
sudo cp YOURCERT.pem /opt/Citrix/ICAClient/keystore/cacerts/
make sure the cert ownership & permissions are correct:
sudo chown root:root /opt/Citrix/ICAClient/keystore/cacerts/YOURCERT.pem
sudo chmod 644 /opt/Citrix/ICAClient/keystore/cacerts/YOURCERT.pem
optional, rehash the certs (creates has value for the new cert and creates system links to it).
BTW here is the official Citrix page on installing a cert in Linux.