I want to create a new user in MySQL with the syntax:

create user 'demo'@'localhost' identified by 'password';

But it returns an error:

Your password does not satisfy the current policy requirements.

I have tried many passwords but they don't work. How can I fix this?

For MySQL 8 you can use the following script:

SET GLOBAL validate_password.LENGTH = 4;
SET GLOBAL validate_password.policy = 0;
SET GLOBAL validate_password.mixed_case_count = 0;
SET GLOBAL validate_password.number_count = 0;
SET GLOBAL validate_password.special_char_count = 0;
SET GLOBAL validate_password.check_user_name = 0;
ALTER USER 'user'@'localhost' IDENTIFIED BY 'pass';
FLUSH PRIVILEGES;