During the booking process an email is sent to the user to validate their appointment. During the email process if PBBooking is unable to find either a default template or a multi language override this will fail with a 404 not found page. The error message will also contain an Error Code 0: No Multi lang override or default template found.
This occurs when there has been a problem during installation and the default system email templates have not been installed, or they have been removed.
To correct this the 3.2.6 release adds a button to the main PBBooking dashboard under Database Tools labelled Restore System Emails. This will restore the default Pbbooking email templates if they have been removed.