Member Avatar for Jackmartini

What are some of the issues that can cause random problems with pdf files downloaded from a website? Sometimes they display a solid black screen, sometimes white, sometimes get a warning window that says only 'adobe', and other times they work fine. There seems to be no pattern - just a random result each time a link is clicked. Similar results in FF or IE. Seems like this should be a simple thing but haven't been able to find a solution. Any ideas would be appreciated.

The page is http://www.thegreatmartinicompany.com/math-worksheets/math-worksheets.html

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— intermittent black/white PDF displays often trace back to how the PDF bytes are delivered, not just the viewer. correctly flagged client variability; the checklist below focuses on server-side causes that reproduce the symptoms you described and gives quick tests to confirm them.

  • Verify HTTP headers. The response should use Content-Type: application/pdf, include a correct Content-Length, and (for progressive/open-in-place behavior) advertise byte-range support with Accept-Ranges: bytes. See MDN on MIME types and range requests: MIME types and Content-Type and Range requests.
  • Do not apply gzip/deflate to PDF responses. Compressing already-compressed binary streams can corrupt plugin rendering; exclude application/pdf from server compression (Apache mod_deflate docs): mod_deflate.
  • If the PDF is streamed by a server-side script (PHP/ASP/CGI), ensure the script sends exact headers, disables output compression/buffering, writes the raw bytes (no extra whitespace/BOM), and closes the connection cleanly. Partial or malformed streams often present as black screens.
  • Check intermediaries (CDN, proxy) that might strip or alter headers, or break range requests.

Quick checks to run from any machine (replace the URL with the PDF link):

curl -I "https://your.site/path/file.pdf"
curl -r 0-99 -D - "https://your.site/path/file.pdf"
curl -o /tmp/test.pdf "https://your.site/path/file.pdf" && md5sum /tmp/test.pdf

Inspect the headers for Content-Type, Content-Length, Accept-Ranges, and any Content-Encoding. If headers look correct but readers still fail, download and open the file locally to rule out on-the-wire corruption, and review server logs for 206/416/500 statuses or aborted connections. These focused checks usually reveal whether the issue is delivery-related (fixable server-side) or strictly client-side.

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Member Avatar for Lusiphur

I just went through about a dozen of them and all came up fine. What I might suggest is you make sure your PDF viewer (Adobe Acrobat Reader) is up to date with the latest version as sometimes version issues can cause viewing incompatibility. Alternately, it could just be latency in the download of the PDF file as each of the files I tested did start off with all black for about 1/4 second before loading on my screen.

You can make sure you have the latest viewer here. As a side note, Adobe likes to package a trial version of McAfee Security Scan Plus with their reader download, you can opt out of this however and I personally don't like it on my system.

Hope this helps :) Please mark as solved once your issue is resolved.

Member Avatar for henduo12

i suggest you use internet explorer, i also have problems with firefox and chrome when trying to view pdf files.

Member Avatar for Lusiphur

<-- Using firefox and having no difficulties whatsoever with the links on the page presented :twisted: 9/10 times issues viewing pdf files boil down to reader version issues or site delivery issues moreso than browser specific issues.

As a side note, I refuse to use Internet Explorer for anything other than testing web content as I'm developing.

Member Avatar for Jackmartini

It seems there are solutions on the client side. But is there anything I can look at on the server side or in my html to make it more relilable? Getting a black or white screen when they expect something else is just a terrible user experience and reflects poorly on site. I use javascript to load the links into a div tag when a category (addition, subtraction,..) is selected. Could that cause links to be less "reliable" than links embedded in the html? Or could there be apache issues?

Member Avatar for Lusiphur

My thought is, if it's at all server-side related it'd be the speed at which the information is being presented to the user. I don't believe that your javascript link system is an issue per-se but more the size of PDF files and speed of file transfer. However, this can be either a server issue or a client issue or neither (in the case of router issues BETWEEN server and client).

As I indicated, I had no issues whatsoever with a random cross-section of links that I opened from the site so it leads me to infer that the issue is either client-side (reader issue/reader version) or server-side (beyond the script, actual server file presentation).

Member Avatar for Jackmartini

Thanks Lusiphur. Good assessment. I guess its just a tradeoff between the benefits you get with the relative universal usability of pdf and some quirkiness in its display. Still, it seems far better than trying to deliver consistent print documents with HTML.

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