ASP.NET Web API request does not reach controller action

Question

I have trouble posting 'large' objects to my web api using the HttpClient's PostAsJsonAsync method. The objects contain a base64 encoded image file.

After a period which seems like the client's timeout setting, the exception

'A task was canceled.'

is thrown by the HttpClient . The timeout is already set very high (10 minutes). This only happens with files larger than ~2 MB. Anything smaller works fine. I know that the request does not even hit the first line of code in the controller method because the first line is a logging line and the log is empty. There are no exceptions in the server event viewer.

It is hard to pin down the issue because the controller works fine when I deploy the web api on my local IIS. But when I deploy it on my Azure VM, it only work for small files. The web.config files are identical.

maxRequestLength is already set high enough.

<httpRuntime targetFramework="4.5.2" maxRequestLength="1048576" />

Instead of IIS hosting in an Azure VM, i've just tried to deploy the API as an app service. The exact same thing happens there.

Answer 1

You can also try setting this limit:

<system.webServer>
    <security>
        <requestFiltering>
            <requestLimits maxAllowedContentLength="1073741824" />
       </requestFiltering>
    </security>
</system.webServer>

Note that contrary to the maxRequestLength parameter, this value is in bytes.