Jenkins Can't Download Plugins? Check if Your ISP Is Blocked

15 October 2024

Symptom: installing or updating plugins fails with timeouts or connection errors to the Jenkins update center.

Cause: some ISP IP ranges get blocked by the Jenkins download mirrors. It happened with Digi (Spain): routing the Jenkins server through a VPN exiting in another country (not Romania) fixed it straight away.

How to check it from the Jenkins host:

curl -I https://updates.jenkins.io/update-center.json
curl -IL https://updates.jenkins.io/download/plugins/git/latest/git.hpi

If it times out from your connection but works through a VPN or another network, it is the same problem.

Workarounds:

Use a VPN or an HTTP proxy (Manage Jenkins > Plugins > Advanced settings).
Download the .hpi file from another network and upload it in Advanced settings > Deploy plugin.