报错如下：

There were errors checking the update sites: SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

解决办法：修改Advanced里面Update Site的URL

把
https://updates.jenkins.io/update-center.json
修改为：
http://updates.jenkins.io/update-center.json

之后点击【Submit】—>【Check now】

然后就恢复正常了：