I am getting this message in the ERROR/DEBUG LOG after people acces the "/amember/signup.php/" page on an aMember install of version 4.2.11. Is someone trying to steal a subscription with some sort of FREE payment plugin, or is this okay and normal? "Sorry, it is impossible to use this payment method for this order. Please select another payment method : Cannot use FREE payment plugin with the product which cost more than 0.0"
This can indicate an error in script configuration or if someone is trying to fool the system. Try to signup as regula user from default signup form and check this yourself, if you get the same error, this is configuration issue.