PDF invoice problem

[ByteFM]

Hello,

I use prestashop version 1.3.1.

i wanted to edit my /classes/pdf.php
I changed line 172:

$textFooter = self::l('An electronic version of this credit slip is available in your account. To access it, log in to the');

to

$textFooter = self::l('An electronic version of this credit slip is available in your account. To access it, log in to the aa');

just to see what happens (yes, I am not a real newby). When clicking on "PDF" in the admin area I got this problem:

Warning: Cannot modify header information - headers already sent by (output started at /var/www/byte.fm/www/shop/classes/PDF.php:1) in /var/www/byte.fm/www/shop/tools/fpdf/fpdf.php on line 1032
FPDF error: Some data has already been output, can't send PDF file

It still remains even after deleting my "aa". I checked all pdf.php files. I got no white spaces or something like that.
Can you help?

Thanks
Christoph

[VNguyen]

Hi,

This issue due to you have used any "echo", or "print_r", or "var_dump" in PDF.php. Make sure you do not use these functions to output something (maybe for debugging for example).

Viet