Although having set the MaxRequestLength and maxAllowedContentLength to the maximum possible values in the web.config section, ASP.Net
MaxRequestLength
maxAllowedContentLength
web.config
Alternatively use the attribute, so the equivalent for an action as resolved by Transcendant would be:
[RequestFormLimits(ValueLengthLimit = int.MaxValue, MultipartBodyLengthLimit = int.MaxValue)]