Fatal error: Uncaught TypeError: mysqli_num_rows(): Argument #1 ($result) must be of type mysqli_result, bool given in /home/u416661785/domains/pdfabook.com/public_html/category.php:26 Stack trace: #0 /home/u416661785/domains/pdfabook.com/public_html/category.php(26): mysqli_num_rows() #1 {main} thrown in /home/u416661785/domains/pdfabook.com/public_html/category.php on line 26