Mac Mini 4 l unable to log in to the user account “xxx”

Hi all, I’ve run into a difficulty trying to use an external SSD as my home folder drive - the boot disk remains the internal drive. On restarting, I get the message “You are unable to log in to the user account ”xxx” at this time. Logging in to the account failed because an error occurred”. I’ve reloaded the OS and updated the password. Still stuck. Also tried with/without the external SSD (Samsung T7). Have you any advice please?