Sometimes you get this error in Ubuntu “Error: Host key verification failed. Please select another viewer and try again”
Just delete the offending key in ~/.ssh/known_hosts .
If you dont know the key or are too bored to search for it, then make a copy of the file and delete everything in it.
To edit form the command line use the command
sudo gedit ~/.ssh/known_hosts
To do this from the GUI
Browse to your home folder. Select View > Show Hidden Files from the menu, or hit Ctrl+h. From there open the .ssh folder and open the known_hosts file and edit