Today, I tried to upload a file around 40M to a library. But it failed with 404 error number. I tried to do the same on my other SharePoint server, successed.

The defferences between these two server is the OS and IIS version. After I tested, the SharePoint based on IIS 7 does not allow me upload one file greater than 29M (include 29M).

This problem is caused by IIS 7 default settings. To resolve this problem, please do following steps:

1. Open C:\Windows\System32\inetsrv\config\applicationhost.config file.

2. Locate to the node configuration - system.webServer - security - requestFiltering - requestLimits. the requestLimits may not existing in this file. Please add this node manually if it is not existing.

3. Set the maxAllowedContentLength proterty and assign the value to this property.

the sample xml is:

<configuration>
        <system.webServer>
            <security>
                <requestFiltering>
                    <requestLimits maxAllowedContentLength="100000000"/>
                </requestFiltering>
            </security>
        </system.webServer>
</configuration>Please keep in mind that this issue is not a SharePoint issue. It is a issue about IIS7. It will occurred on not only SharePoint environment.