|Right-click and deletion of reservation from the Daily Reservation screen gives this error.|
|Update to version 2004. This issue has been fixed.
Try deleting the invoice using SHIFT+CTRL+ALT+D from the contact data screen. You will then need to recreate the reservation.
This could be an invalid character in a POS item, such as an apostrophe (') or quotation mark ("). Edit POS inventory and check all names, and remove these "illegal" characters.