Resolution
This happens most of the time because of a misconfiguration of your proxy. To check it, we suggest you do a HTTP get using the command below from the same machine you have install your CloudBees Jenkins Enterprise controller.
curl -u user:passwd -x my-proxy:888 https://jenkins-updates.cloudbees.com/update-center.json?uctest
This article is part of our Knowledge Base and is provided for guidance-based purposes only. The solutions or workarounds described here are not officially supported by CloudBees and may not be applicable in all environments. Use at your own discretion, and test changes in a safe environment before applying them to production systems.