Password Plugin for 0.51

[jmacgowan]

I've installed an mostly configured the password plugin, and I'm using Roundcube 0.51.

I'm trying to change passwords that are stored in a MySQL database.

After navigating to Settings > Password I attempt to change user's password and upon submission I get SERVICE CURRENTLY NOT AVAILABLE! Error No. [500]

The interesting thing is that it only happens when I make a valid reference to a MySQL database.  What I mean is:
$rcmail_config['password_db_dsn'] = 'mysql://:@localhost/mail';
Results in the error.

$rcmail_config['password_db_dsn'] = 'foo';
and/or
$rcmail_config['password_db_dsn'] = 'mysql://:@localhost/mail';
Will just say "New password cannot be saved"

Which leads me to believe that I have a configuration issue, but I am not sure where to start.

Thank you for any insight or help with this issue.

[SKaero]

What shows up in the roundcube error log? Have you double checked the update query?