Permission denied when I SSH access to EC2 instance

Question

Please help me, when I am trying to connect to my EC2 instance using SSH, I am getting a key error message. Please help me rectify it.

Permission denied (publickey)

This is the error I am getting.

Answer 1

These are common reasons that can cause this error are as follows:

1. Trying to connect with the wrong key. Are you sure this instance is using this keypair?
2. Trying to connect with the wrong username. ubuntu is the username for the ubuntu based AWS distribution, but on some others it's ec2-user (or admin on some Debians, according to Bogdan Kulbida's answer)(can also be root, fedora, see below)
3. Trying to connect the wrong host. Is that the right host you are trying to log in to?

Note: This will also happen if you have messed up the /home/<username>/.ssh/authorized_keysfile on your EC2 instance.