Hello I am sorry but I have exactly the same problem.
6:56 pm
Warning: Cannot modify header information – headers already sent by (output started at /home/sites/site190/web/blog/wp-includes/template-functions-general.php:607) in /home/sites/site190/web/blog/wp2pdf/fpdf.php on line 1278
FPDF error: Some data has already been output to browser, can’t send PDF file
There is no <?php or ?> at this line. Can someone help ? Thanks