Ubuntu server 16.04 boot issue
After creating an instance from Ubuntu 16.04 Server installer and opening the console, the instance shows a black screen or a message about /dev/sda1:clean.
Cause
This is a known issue in the Ubuntu 16.04 Server.
Solution
Use the console options provided to send CTRL + ALT + F2 to switch virtual terminals to cause a login prompt to display.
Alternatively, log in via SSH.
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