Error Pwd Reset – An unknown error occurred. Please try again later

You’ve likely got an overly aggressive cache – or you’re invoking the form incorrectly.

That message indicates an expired nonce, which is a device to prevent the form from being submitted remotely (i.e. spammed).

If you have a cache application (either plugin or at the server level), if it does not recognize the nonce, then you need to provide an exception in your cache for the page the reg form is on.