Why does Jenkins say “This Jenkins instance appears to be offline”

Question

I have a fresh install of Jenkins 2.32.2 on Ubuntu. Opened a browser on the instance and get to a page titled Offline, with the message \"This Jenki

Answer 1

I'm working on a Mac, and in my case, it turned out that the version of Java Jenkins was using (1.8.0u66) wasn't up to date enough. I had both Java 11 and Java 14 installed, but the jenkins-lts script was coded to force use of Java 8. Rather than install a more up to date JDK 8 installation, I modified the script to run ${JAVA_HOME}/bin/java and set JAVA_HOME to the JDK 11 installation.

Answer 2

In my case i have changed https to http in URL line of /var/lib/jenkins/hudson.model.UpdateCenter.xml file and restart the jenkins, its start functioning.

Answer 3

in case you are running jenkins in a container and vi is not installed access your container in interactive mode

docker exec -it jenkins-ci /bin/bash

use this sed command to replace https with http

sed -i 's/https/http/g' /var/jenkins_home/hudson.model.UpdateCenter.xml 

Answer 4

Enter this before running Jenkins.

# iptalbes -F

It may be because of the firewall.

Answer 5

On MacOS: 10.11.6

Step-1: Go to /Users//.jenkins

Step-2: Open the file: hudson.model.UpdateCenter.xml

Step-3: CHange the value of "default" from "https://xxx" to "http://xxx"

Answer 6

I make no claims about this, especially Java related (I personally cannot stand the language), but on my Ubuntu 18.04 L/T, I needed to stand-up a standalone Jenkins instance; So I installed both the Java on which Jenkins appears to be dependent and Jenkins itself

sudo apt install openjdk-8-jdk jenkins

Then I updated the Jenkins defaults

sudo gvim /etc/default/jenkins

... inserting the following at the top of the file - only because editing /etc/init.d/jenkins appeared to serve no purpose as it had no effect whatsoever ...

JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64/jre/bin/
PATH=$JAVA_HOME:$PATH

Finally, save & quit ... then attempt Jenkins restart

sudo service jenkins restart

HTH - it certainly worked for me :-)