I know that you already inserted the formkey, but I had the same problem and I discovered that I was using the formkey in the wrong way. 1 - Make sure that you use this code to insert the formkey: <? php echo $this -> getBlockHtml ( 'formkey' ); ?> 2 - The code should be right after the line: <form action=" <? php echo $this -> getPostActionUrl () ?> " method="post" id="login-form"> 3 - Make the change in the right files: app / design / frontend / base / default / template / customer / form / login . phtml app / design / frontend / base / default / template / customer / form / register . phtml or, if you are using a custom theme: app / design / frontend / COMPANY / THEME / template / customer / form / login . phtml app / design / frontend / COMPANY / THEME / template / customer / form / register . phtml Good luck :)