c# Asp Web API: HttpException: Maximum request length exceeded.

Question

This might be a common question, but my situation is not so common.

I an sending a serialized image into an Asp.net Web API method and am getting this error:

System.Web.HttpException: Maximum request length exceeded.

at System.Web.HttpBufferlessInputStream.ValidateRequestEntityLength()

I searched online and found a lot of answers saying to do this in the web.config:

<system.web>
  <httpRuntime maxRequestLength="40960" /> // 40MB (default)
</system.web>

<system.webServer>
  <security>
    <requestFiltering>
      <requestLimits maxAllowedContentLength="2147483648" /> // 2GB
    </requestFiltering>
  </security>
</system.webServer>

but when I do that all of my other API calls fail. I get:

500 - Internal server error.

and no code executes in the API calls. they all fail.

So I cannot use this setting to allow bigger files to be send into the API.

What should I do?

thanks.