Unable to install Jenkins on Ubuntu 20.04 [closed]

Question

I am trying to install Jenkins on my Ubuntu EC2 instance and I performed the following steps to install but couldn't install it.

$sudo apt update
$sudo apt install openjdk-8-jdk
$wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -
$sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
$sudo apt update   <--------- (Here I am getting below error)

root@ip-172-31-44-187:~# sudo apt update

Ign:1 https://pkg.jenkins.io/debian-stable binary/ InRelease Err:2 https://pkg.jenkins.io/debian-stable binary/ Release Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 151.101.154.133 443] Hit:3 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu focal InRelease Get:4 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB] Get:5 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB] Get:6 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu focal-backports InRelease [101 kB] Reading package lists... Done E: The repository 'http://pkg.jenkins.io/debian-stable binary/ Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.**

Answer 1

Instead of upgrading every package with apt-get upgrade, I used: sudo apt install ca-certificates

And then: sudo apt-get update worked just fine.

Answer 2

I was facing same issue when I tried to install jenkins in AWS ec2 instance (Ubuntu 20.04). Below steps helped me.

1. Update Ubuntu packages and all installed applications

sudo apt-get update -y
sudo apt-get upgrade -y

2. Next, Install JDK

sudo apt install openjdk-11-jdk -y

3. Verify Java version

java -version

4. Add gpg key for jenkins installation

wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | apt-key add -

5. Add the repository address to our /etc/apt/sources.list.d file

sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > \
e>     /etc/apt/sources.list.d/jenkins.list'

6. Update our package list again

sudo apt-get update -y

7. Install Jenkins

sudo apt-get install jenkins -y

It worked like charm!