Troubleshooting Ubuntu Installation

Known Issues and frequent Questions#

"Host key verification failed" Error Message

Some users working on existing servers receive the following error message:

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@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
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IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:JWhuzo4SNV8rJNp9-THIS-IS-AN-EXAMPLE-L3N1GIjdM6VENIE.
Please contact your system administrator.
Add correct host key in /Users/user/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/user/.ssh/known_hosts:30
ECDSA host key for 55.XX.XXX.46 has changed and you have requested strict checking.
Host key verification failed.

This simply indicates that the key on the server has been changed. One solution is to delete the offending key from your local computer so this error goes away.

You will need your IP address and simply run this command using your IP address.

# example ssh-keygen -R 55.444.44.111
ssh-keygen -R your-ip-address-here

Then you should be able to log in to the server correctly.