What are you trying to add? "custom footer" could mean anything, is it text? Some HTML? An Image? For me to edit the PDF footer, I'd modify the function Ticket2PDF->Footer() found in include/class.pdf.php around line 94, adding text either before or after the existing entries to the footer, either line 104 or 100 etc..To add some "text", try using $this->SetFont('Arial', 'I', 9); // What size & font, must be set before the text.$this->WriteCell(0, 7,"Your text here"); // Actually insert some text into the PDFWhy yours broke:Attempting to print anything there will set an HTTP Header, which causes the download to fail, you can't output (echo/print/printf/etc) anything at all as it will set it's own headers when the file is ready to be sent. To add to the PDF output you need to add to the PDF object using it's methods.More info: http://stackoverflow.com/a/8028987