.NET Http file upload intermittent problems

We have had problems for the past year whereby when users upload files to the server very few files will just not upload via a simple HTTP form.

These files have been of varying sizes and types but for some reason they will not upload. Often ZIPing them up will help resolve the problem but ideally the user should not have to do this anyway.

Common pitfalls that I have ruled out are:

File size (maxRequestLength="2097151" Set to maximum to prove it is not file size)
Request timeout (Given ample time, some files won't even move past a low percentage of the upload)
Various upload components tried as well as the standard asp:FileUpload

I personally can't work out why these filse can't be uploaded via HTTP. Does anyone have any insights into this problem?

I have had a suspicion in the past that it could be files that were created on a Mac, however that is entirely a guess and not factual. Lots of files are created on Macs and uploaded perfectly fine so that is why I am dubious that this is the reason why the files won't upload, especially because sometimes I can re-save them from a PC and it makes no difference.

Thanks in advance

Update : in our particular situation, we found out that the firewall was the culprit. The problem happened with various file types and various clients. Sometimes, removing a single byte from the file, made it go through the upload.We use a Zyxell USG200 and the Anomaly Detection option (ADP) is what makes all so weird. Packets were analyzed and anomaly logged but passed through. We tried to disable rule by rule but only disabling the whole thing made it work. Hope this can help someone.

Roger 2009-11-16 06:45:40

ansaurus

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.NET Http file upload intermittent problems

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