As we all know in ASP.NET we can configure the maximum length of the request using httpRuntime's "maxRequestLength" attribute (By default this is set to 4KB and SharePoint uses 50MB as a default value). While this setting works with IIS 6.0, in IIS 7.0 a new attribute "RequestLimitsElement" needs to be configured as well to allow uploading files larger than 30 MB through HTTP.
More information can be found here and KB944981.
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