For low memeory VPS (Free memeory less than 512MB ), our script use MyISAM instead of InnoDB by default

If you want enable InnoDB, please make sure your VPS memeory is enough to get mysql work. 

Then, vi /etc/my.cnf, delete below 2 lines and restart mysql:

innodb=OFF
default-storage-engine=MyISAM

If you see below error when restart mysql,
“InnoDB: Fatal error: cannot allocate the memory for the buffer pool”
You will need change some parameter eg. innodb_buffer_pool_size to use less memeory, restarted the MySQL and it was done , error gone .