Normally this issue has a simple solution but people tend not to read whats is required to eliminate the error:
When you run the ssh command following error is received:
ssh issueto remove this error, you just need to edit single line on the following path (I am using nano as editor):
 nano /root/.ssh/known_hosts
ssh issue1Remove the line which corresponds to the IP address which you were trying to access via ssh. save the file and again try to ssh.