ERROR 1396 (HY000): Operation CREATE USER failed for 'username'@'localhost' IDENTIFIED BY 'mypassword';

Question

Mistakenly I deleted my root user from my mysql.user table.

delete from mysql.user where user=\'username\';

To make same root

Answer 1

This user must be referenced in other tables from the mysql system schema. I would recreate the user the same way you deleted it:

INSERT INTO mysql.user (user, host, password)
VALUES ('root', 'localhost', PASSWORD('pasw'));

Then

FLUSH PRIVILEGES;
GRANT ALL ON *.* TO 'root'@'localhost';

Yet another reason to never mess with this schema (sorry, I couldn't help).