Downloading invoices (PDF) does not complete

We have a magento commerce site running on an IIS 6.0 server with PHP 5.2.11 running magento.

Whenever user tries to use the print to download pdf to their computer from the admin panel the download does not complete. I can see that the full file is downloaded to the computer but the browser still keeps on saying it is downloading. Thi开发者_如何学Gos means the file gets save with a .part in the end and users cant open the file as pdf. If i remove .part extension created by firefox then i can view the pdf correctly. This means the data is sent to the browser from server in full but download does not terminate.

See headers below on response while starting to download the pdf

HTTP/1.x 200 OK
Cache-Control: must-revalidate, post-check=0, pre-check=0
Pragma: public
Content-Length: 1456781
Content-Type: application/pdf
Content-Encoding: gzip
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Last-Modified: Fri, 18 Dec 2009 10:23:37 +0000
Vary: Accept-Encoding
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET, PHP/5.2.11
Content-Disposition: attachment; filename=invoice2009-12-18_10-23-37.pdf
Date: Fri, 18 Dec 2009 10:23:37 GMT

I guess it is something to do with not closing the connection after sending the whole file through? Please help!

Thanks.

I had the exact same problem (Apache), I temporarily solved the issue by turning off the gzip compression on the responses. My guess is that the size being reported by Magento (which it gets from a strlen() call on the PDF content) to the browser does not reflect the real content size that the browser gets given that it gets compressed later on. This results in the browser waiting for more data which is never going to arrive..

edit: worth noting that in my case I was going to the site through a reverse proxy.

Have you tried explicitly calling exit; after you output the pdf data. Sounds like an IIS thing.