Maximum request length exceeded.

Issue:
The file upload size on your machine or web app is too small. The default file upload size for IIS is 4096K. The file size the user is trying to add can be retrieved (using the ELMAH log here) by looking at the Content-Length header property:

HTTP_CONNECTION:keep-alive HTTP_KEEP_ALIVE:115 HTTP_CONTENT_LENGTH:6414851

In this example it is just over 6Mb

Solution:
You can add/update the HttpRuntime property in the machine or web config files, depending on at what level you want to set the size. For web-server level, impacting all web-apps running on that machine specify the following in the node of the machine.config file to allow less than 1Mb:

      <system.web>

<httpRuntime maxRequestLength="1000" />

If you want to set it, bigger, smaller or block at the web-app level you can specify it by adding the property above to the web.config file of that web app and it will only affect that web app.

For example I would like to maintain the default 4096K size limitation on my server except for the accounting web app and therefore set the accounting web-sites virtual directory web-config file to handle 8Mb file uploads:

      <system.web>

<httpRuntime maxRequestLength="8192" />