I use pie-register 2.0.21 for wordpress 4.7.5
When I clicked on forget password link,we received an email with link to reset password.
But this link never works.We have tried out every possibility.
Clicked on linked from email.
Carefully copied and opened it new incognito window.
Repeated whole cycle of forget password more than 10 times for 2 users.
But every time got same error,saying “This Reset key is invalid or no longer exists. Please reset password again!”
oh!I think I found what cause this problem.
I use the keyword ‘function get_password_reset_key’ to research my project
and I found another activated plugin[Theme My Login] use the same function
so I go to close the plugin and then it work!!