# config/packages/security.yaml
security:
  # ...
  encoders:
    App\Entity\User:
      algorithm: "argon2i"
      migrate_from: "bcrypt"

// src/Repository/UserRepository.php
namespace App\Repository;

// ...
use Symfony\Component\Security\Core\User\PasswordUpgraderInterface;

class UserRepository extends EntityRepository implements PasswordUpgraderInterface
{
    // ...

    public function upgradePassword(UserInterface $user, string $newEncodedPassword): void
    {
        // this code is only an example; the exact code will depend on
        // your own application needs
        $user->setPassword($newEncodedPassword);
        $this->getEntityManager()->flush($user);
    }
}