The troubleshooting was very painful process. At first, I thought it’s MySQL issue as the error page suggests, but I keep failing to reboot MySQL process. It seemed that the database file was corrupted, and I needed to give up the database file. That is when I started searching how such things happens.
One of the user tutorials is very helpful, and the site is rebuild and up and running.
After several cups of coffees and trials and erros, I am happy to see it’s finally working.