I can't log in as admin on my test system atm due to this. (not too serious for me as I have no data on the test system).
1. Install the module.
2. Set hash method to md5.
Now with users who still have a phpass has can log in (and the hash will be converted to an md5), but if a user only has an md5 hash, the following error messages are given:
* Sorry, unrecognized username or password. Have you forgotten your password?
* warning: array_fill() [function.array-fill]: Number of elements must be positive in C:\wamp\www\drupal-6.3\includes\database.inc on line 240.
* warning: implode() [function.implode]: Invalid arguments passed in C:\wamp\www\drupal-6.3\includes\database.inc on line 240.
* warning: array_keys() [function.array-keys]: The first argument should be an array in C:\wamp\www\drupal-6.3\modules\user\user.module on line 514.
* user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1 query: SELECT p.perm FROM role r INNER JOIN permission p ON p.rid = r.rid WHERE r.rid IN () in C:\wamp\www\drupal-6.3\modules\user\user.module on line 514.