Hi,
Have you got password policy enabled - it may be the passwords do not pass the policy check. Add the line to config.php :
$CFG->passwordpolicy = 0; // Remove password policy
Have you got password policy enabled - it may be the passwords do not pass the policy check. Add the line to config.php :
$CFG->passwordpolicy = 0; // Remove password policy
Alternatively use the Site admin UI to do so.