Why Jenkins says "Server rejected the 1 private key(s)" while launching the agent?

I solve this issue following below steps:

From the target slave node's console

1. Switch to the root user:

sudo su

2. Add a jenkins user with the home /var/lib/jenkins (Note: I am keeping my home directory in /var/lib/jenkins):

useradd -d /var/lib/jenkins jenkins

From the Jenkins Master

Copy the /var/lib/jenkins/.ssh/id_rsa.pub key from the Jenkins user on the master

From the target slave node's console

1. Create an authorized_keys file for the Jenkins user

mkdir /var/lib/jenkins/.ssh
touch /var/lib/jenkins/.ssh/authorized_keys

2. Paste the key from the Jenkins master into the file vim. Save with :wq!

3. Make sure the files have correct owner and permission.

chown -R jenkins /var/lib/jenkins/.ssh
chmod 600 /var/lib/jenkins/.ssh/authorized_keys
chmod 700 /var/lib/jenkins/.ssh