There are dozens of reports in the Google Webmaster Help forums that the submit URL to Google via the Fetch as Googlebot feature is not working.

I tested it myself and it is indeed not working.

When I navigate to the “Fetch As Googlebot” under the “Diagnostics” section. I then fetch a URL and it works. After you fetch the URL Google often lets you submit it to the index. When you try that, it returns an error that reads, “There was an error processing your request.”

Here is a picture I mashed up of the tool with the error:

I am not sure how used this feature is, but John Mueller from Google said:

The issue was first reported last Thursday.

Forum discussion at Google Webmaster Help.