Nada, me sigue saliendo el mismo error
Cita: Warning: Cannot modify header information - headers already sent by (output started at /home/content/c/e/j/cejarcon/html/customerclose/cotizador/cotiza1.php:77) in /home/content/c/e/j/cejarcon/html/customerclose/cotizador/mpdf/mpdf.php on line 7062
Warning: Cannot modify header information - headers already sent by (output started at /home/content/c/e/j/cejarcon/html/customerclose/cotizador/cotiza1.php:77) in /home/content/c/e/j/cejarcon/html/customerclose/cotizador/mpdf/mpdf.php on line 1713
mPDF error: Some data has already been output to browser, can't send PDF file