Select this one if in doubt: Argon2i is a modern key derivation function that was selected as the winner of the Password Hashing Competition in July 2015. Argon2i is not available on this system. This is sad since it is a modern password hash algorithm and the winner of the Password Hashing Competition in July 2015. It is easily available on all platforms since PHP version 7.2. There is no sane reason to run PHP >7.2 without argon2i. Please reach out to your hoster to fix this and select this hash algorithm as soon as it is available.