Jenkins - Update information obtained: 不可用 ago；

Jenkins add plug-ins

jenkins plugin Tip: Update Information Obtained: unavailable ago;

Edit hudson.model.UpdateCenter.xml file 
HTTPS: // updates.jenkins.io/update-center.json to http protocol. 
Then restart Jenkins

If you are using the default tomcat war package. Files in the current directory are hidden by default user directory;

/root/.jenkins/hudson.model.UpdateCenter.xml