Documentation

Large Files

If there is a need to support very large files or very long URLs, tweak web.config values as follows:

<requestLimits maxUrl="2000" maxAllowedContentLength="209715200" maxQueryString="2000"></requestLimits>
[...]
<httpRuntime requestValidationMode="2.0" relaxedUrlToFileSystemMapping="true" maxRequestLength="204800" maxUrlLength="2000" maxQueryStringLength="2000" />

Additional info could be wound here and here.