Ubuntumysql cannot start simple troubleshooting _ MySQL

My website has not been on for a long time. I want to open it and find that it cannot be opened, so I found a series of reasons. Vps is not working. dns resolution is faulty. after a domain name has a problem and a simple troubleshooting, my vps service is commercially available for the bricklayer (bandwagonhost ), after restarting, I still failed to access my website for a long time. I tried to open the website and found that it could not be opened, so I found a series of reasons.

Vps is not working. dns resolution has a problem with the domain name.

After a simple investigation, my vps service was commercially available as a bricklayer (bandwagonhost). After I restarted the service, I still couldn't access it. later I checked my domain name hosting (dnspod ), it seems that there is no problem. Finally, I checked the domain name provision (freenom). the domain name has expired for one year, and it should be okay.

Later, after reading it for a while, I realized whether the apache server was not started.
Restart: sudo apache2ctl-k restart
You can access it.

However, mysql is still unavailable.
So I tried to restart: service mysql start
The error indicates that the instance cannot be started, and there is no reason to write it (the ubuntu system on the server is relatively small, and the error message is incomplete). after searching for the system for a long time, I don't know what the problem is.

Later, I found the information on the internet and found the ERROR log (in/var/log/mysql). The ERROR cause is [ERROR]/usr/sbin/mysqld: unknown variable 'default-character-set = utf8'

After checking the information on the Internet, I found that I had to change the default-character-set = utf8 in the mysql configuration file my. cnf to character_set_server = utf8. After I tried it, I could =
(My. cnf is in/etc/mysql)
Really weak =