Thought this was worth blogging as it's a real gotcha in .NET. Like PHP there is a default file size specified which you need to tweak to allow big file uploads. Unlike PHP, .NET fails silently and also doesn't point out the other settings which need tweaking like request size.

Below is a sample web.config which gives a much bigger upload size. Useful for allowing those big uploads to the server even if these days we seem to pump it out to a CDN like Akamai as fast as we receive it.

web.config

Also a useful tip. Any changes or saves to the web.config will automatically result in the application being restarted which is nice, though may cause you to be logged out if you're not using out-of-process sessions.