I'm having trouble to get the registration page up and running. This is the message I get after filling in the fields:
Notice: Undefined variable: user_id in .../plugins/membership/membershipincludes/classes/membershippublic.php on line 1710
Can you please take a look at it. Looks like a workaround has been implemented but this line uses $user_id which has not been defined in case of an error.