FPDF error: Some data has already been output, can't send PDF file

[Peper]

Took me many hours to figure this out

Hope this will help someone else - old and new FPDF ver.

 

I got addon with pdf invoice and packing slip, but when generating pdf file I was getting FPDF error: Some data has already been output, can't send PDF file

or

the page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression

 

So, open admin/pdf_invoice and packingslip.php and edit as follows

 

find on top of page:

require('includes/application_top.php');

 

replace with

 

require('includes/application_top.php');

while (ob_get_level())

ob_end_clean();

header("Content-Encoding: None", true);