Why does Jenkins say "This Jenkins instance appears to be offline"

Why does Jenkins say "This Jenkins instance appears to be offline"

jenkins offline

jenkins

How does Jenkins resolves conflict in plugins version dependency

jenkins jenkins-plugins offline

jenkins

jenkins kubernetes jenkins slave node is offline

jenkins kubernetes offline slave

jenkins

can I bundle node_modules and do npm install from the bundle?

node.js jenkins npm offline

jenkins

Jenkins 2.89.3 "This Jenkins instance appears to be offline"

java macos jenkins offline

jenkins

Jenkins on Raspberry Pi

jenkins plugins raspberry-pi offline

jenkins

Is it possible to start Jenkins without any plugin?

jenkins offline

jenkins