Why does HttpPostedFileBase error out on large files before server side validation gets called?

Question

If I disable client side validation

<add key="ClientValidationEnabled" value="false" />
<add key="UnobtrusiveJavaScriptEnabled" value="false" />

and try to upload a file that's around 11 MB which sets the file to a HttpPostedFileBase memeber

    [ValidateFile]
    public HttpPostedFileBase StudentImageFileBase { get; set; }

I can't even get my custom validation code to get called. As soon as I hit the submit button I see this error message. I can get client side to work, but what if it's disabled in the users browser? Am I stuck showing this message to the user? Something isn't right, shouldn't I be able to upload large files? I'm not trying to in my app but I have to combat against it server side right?

enter image description here

Can you please clarify what kind of help you are looking for? Clearly you know how to solve it since it is first search result for given error - http://stackoverflow.com/questions/3853767/maximum-request-length-exceeded, so I assume you are looking for some sort of explanation why this check is before custom ones? — Alexei Levenkov, Feb 23 '15 at 04:07
How do I validate against files this size on the server if my server file validation code never gets triggered? I'm looking to see if the httpexception is from the size alone or if there is some other reason why this could be thrown? — chuckd, Feb 23 '15 at 04:50

score 2 · Accepted Answer · edited May 23 '17 at 12:34

Look here again. Add appropriate code to your web.config (1GB for example):

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

<configuration>
    <system.web>
        <httpRuntime maxRequestLength="1048576" />
    </system.web>
</configuration>

Now it should allow uploading files up to 1GB and you can check the size on server side:

public ActionResult Foo(HttpPostedFileBase file)
{
  ....
  if(file.ContentLength > 536870912) //512MB
     ....
  ....
}

Why does HttpPostedFileBase error out on large files before server side validation gets called?

1 Answers1