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  1. #1

    Strange file download problem

    Hi, as a new user I hope this is the right forum for this problem.

    Users of my web site, running MD-Pro, a PostNuke (php-based) clone, suddenly started to report difficulties downloading files from the download module. We assumed it was the download module and spent ages diagnosing it, uploading fresh versions etc. After some time someone had the bright idea to see if the files could be downloaded direct (using the URLs) to eliminate the web application.
    We found:
    • Some users can download all files from the server with no problems.
    • Some users can download some files but not others.
    • So far as we can tell only MS Word files are affected, but not all.
    • The files on the server are not corrupted and there are no permissions issues
    • Disabling antivirus and firewalls locally makes no difference.
    • REloading fresh originals to the servedr does not help.
    • The host reports that no changes to the server have been made recently.
    We have discovered that files in the web root are OK. The furhte down the directory structure they are, the less likely they are to download. Performance varies according to the browser in use. According to the host technical support, 'Firefox appears to be returning the data from its own cache. IE is only doing so for root. For the other places IE tries to download the file but stops receiving at exactly the same number of bytes from different locations.'

    Using another server on a different host, the problem disappears so it must be due to the host setup in some way. Diagnosis is difficult because the host technical support can't reproduce it.

    Platforms include Mac, Windows and Linux and browsers include IE7, Firefox and Safari. One user with Mac isn't having problems, another with Mac is. All others reporting problems are on Windows. Users are at different locations, using different ISPs so it is unlikely there are common local problems.

    The only common element I can see is that the ony files causing trouble are MS Word, though some of these do download OK

    We have run out of ideas why this should be happening. How can some users have problems with the same files on the same server and others not?

    What could have happened to cause this problem on a site that has been functioning correctly for several months on this server?

  2. #2
    Join Date
    Aug 2005
    Have you checked the headers sent by the server?

    Maybe the data is sent through upper provider with caching proxy,
    and they are doing something strange, or sending a bit different header.

    I would collect the headers from people with and without the problem and compare.

  3. #3
    Thanks for the suggestion, I will talk to the host technical support and try to arrange this. Wouldn't know how to do it myself.

  4. #4
    Join Date
    Aug 2005
    In IE (on XP), I think you can see the property of the page, but I don't remember exactly.
    With FireFox, there is a extension called LiveHttpHeaders, and it's very usefull.

    There are other tools, too.
    And the host can't do it for you.
    Each users/visitors has to check the headers and report it to you (or the host if they are willing to go that far).

    And then, you have to compare them.
    But it can be another cause, and you may find nothing, after spending lots of time...
    Still, by doing things it, you can be sure about one possibility and it can help narrowing down the possibilities.

    Maybe someone else has better ideas and you can avoid doing these.
    Wait at least for a day or two to see the opinions/suggestions of other users, unless it's urgent.

  5. #5

    Host recommended The problem files returned 'connection failed or site not found'. Others returned headers. Host is investigating.

  6. #6
    We've now established that the problem is confined to certain MSWord files. Some will not download wherever they are placed in the site. Others present no problems. Downoading, reloading, renaming makes no difference to the problem ones. ASCII or binary, via site/php, no difference.

    Their properties show no difference of version etc among the details that Word reports.

    However, renaming them or resaving them to .rtf completely resolves the problem adn they will download form anywhere.

    So what on earth is happening, bearing in mind that none of these files presented a problem a few days ago?

  7. #7
    Join Date
    Aug 2005
    It might have something with mime setting, and maybe the cache setting of some users.
    You may want to ask the host about ANY CHANGE they have done to their server setup, such as version up, configuration modification/clean up, etc.

    Oh, if it's a windows host, please forget what I said.
    I don't have much experience in that area.
    Sorry if that was the case and I confused you rather than help you..

  8. #8
    We're pretty sure it isn't mime setting because (apparently) exactly identical files with .doc extensions behave differently - one will download from anywhere on the site, another won't download at all. Even changing the name (though not the extension) makes no diference, nor downloading them, copying and pasting and reloading!

    The host has admitted they changed thier firewall but that was a couple of months ago, before the problem arose, and we have tested with the firewall open to a particular IP where there were problems.

    Cache settings: again unlikley, unless all the users affected all altered their settings recently.

    But even if any of these were the case, we have the difficulty of explaing how two files of apparently identical type can behave differently.

    If I could pin that down we might be near a solution. If not I think I will just have to change host, though I'll have to have a test run somehow to make sure the problem doesn't happen again. I do at least know that on one other server I use the problem does not exist - the same files that create problems now download fine there.

    I'm totally baffled, so is the host.

  9. #9
    P.S. Its not Windows.

  10. #10
    Join Date
    Aug 2005
    Well, if it depends on the file type, I still suspect mime type setting, somewhere.

    One way of checking is to use EtherReal or tcpdump and check the DIFFERENCEs
    in the requests and responses (and especially the header part) at the host
    for the user who can download and who can't.

    The key is finding the "differences".
    To find them, you need to gather data.

    Trying to download with wget is another way of seeing things.
    You can use the -S option, and it will print the server response header.

  11. #11
    We've now tried this. We're getting no useful data from the 'problem' users because after connecting to the server we get

    HTTP request sent, awaiting response...

    It doesn't time out, it jsut waits, and waits.

    Host is upgrading Apache as "there is one MS Word related bug in the Apache bugzilla, it doesn't appear to be related but if we've got the very latest Apache we can rule this out"

    We can only hope.

  12. #12
    Join Date
    Mar 2004
    This looks better in the Technical Forum. Moved.

  13. #13
    This problem has now been solved. Here is the comment from the web host:

    I'm SO glad this is finally fixed!! Wow. Well, this was really the last resort - we'd tried everything else we could, firewalls, file types, mimetypes. There was no bug in the Apache bugzilla either open or closed that matched what we were experiencing however there was one bug related to MS-Word documents so I figured it was worth a try, I'm so glad I did!
    According to my email client you've sent 59 emails regarding this matter, implying I've sent 59 back - 118 emails, I think this would rank as the 2nd largest support ticket in [our] history (the other one was simply ridiculous)!
    I'll update Apache on our other servers now, just in case someone else runs into this problem. Thanks for helping in getting to the bottom of this very tricky issue!

    I would like to thank extras for the very valuable help which helped direct us to a solution.

  14. #14
    Join Date
    Aug 2005
    You are welcome, and thank you for the update.
    I've not even imagined it was an apache bug.
    Now, if someone has similar case, we know what to suggest.

    Oh, and the host seems to be a really good one.
    If they agree, would you want to share their name?

  15. #15
    Yes, why not, they deserve a pat on the back. . Good prices and absolutely excellent support, as you see.

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