Is there a way to change the error message that users receive when they try to register for an event online for which the registration date has passed? Currently the message is: ! ERROR Registration for this event ended on April 25th, 2016 12:00 PM.
I think it is Possible to customize the error, On your install, visit the Form Registration.php in CRM/Event/Form directory.
The the error message is found in the function checkValidEvent(XXXX). and the line looks like this
CRM_Core_Error::statusBounce(ts('Registration for this event ended on %1', array(1 => $endDate)), $redirect);