Enter to this link and you'll get the following message:
Oops! Something Bad Happened!
Basically, I got this message when I tried to post an question and encounter validation error (do to missing tag or something), so the page returned to me with this new url. after clicking on the new url in the address bar to refresh the page, I got this error page.
I just want to make a point, why use a different url for the http post action? using the same url, for both get and post, will reduce the confusing for the url changing in a validation failed situations.