50MB SharePoint KB900900 WebDAV, 50MB SharePoint KB900900 WebDAV, 50MB SharePoint KB900900 WebDAV!
Why am I lapsing into nonsensical technobabble? I’ll explain.
Recently, we were working with a client who kept running into failures when they downloaded large files from SharePoint 2007 using a UNC WebDAV connection. As you may recall, in SharePoint 2007, documents hosted in a site URL like http://server/site/library can also be addressed using UNC as \\server\site\library
Through experimentation we discovered that 50MB was a critical cutoff in file size. It took a while, but eventually we stumbled upon an easy to remember Microsoft KB article number, 900900.
http://support.microsoft.com/kb/900900
It turns out there was a security fix to prevent a rogue site from attacking a local PC by sending it an extremely large file. The update established a maximum size (exactly 50MB!). This can be adjusted using the registry key FileSizeLimitInBytes (in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WebClient\Parameters )
However, this article is extremely hard to find. Although one of the most likely sources of a Microsoft WebDAV file is SharePoint, nowhere on this page is SharePoint mentioned. Hence my nonsensical ramblings – in hope that it will help more people with this symptom find this post, and, then, the nearly hidden Microsoft KB article. Good luck!
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