When slot=error is displayed

A customer books a time slot from an android mobile phone, when he reaches Booking Confirmed page, instead of closing the page he uses the back

If you have encountered an error while booking your slot for the VITEEE and the system is displaying

error_ replication slot is active for pid “We are sorry, but this time slot is no longer available Please refresh the page and try another time slot Thank you ”

error_ draggable element must have an item slot Slot Problems