A number of months ago, we had to put our Jenkins servers/slaves into a secure dev environment with limited external access but I have pointed Jenkins updates to a proxy server that has been working.
I hadn't checked for updates in a while, but noticed today that about 28 days ago it stopped checking. When I try forcing an update check I see the error:
Signature verification failed in update site 'cloudbees-proprietary' (show details)
but I don't know what the issue is. Clicking the "show details" link doesn't seem to do or show anything. All searches for a solution have come up empty. We are using the cloudbees free plugins such as Folders.
Thoughts?