Just tried to log into my sheilayoshikawa Twitter account and received the above message. Was not logging in for any serious purpose, so am instead assailed by sudden nostalgia for days when there were REAL error messages, ones which gave you no clue whatsover about what was wrong. Still do get those sometimes, but tend to be associated with V. Serious Meltdowns involving blue screen of death and stange series of numbers rushing over screen, which is not a situation where you can have a good old nostalgic wallow.
Sometimes they would be a bit like the one above, implying that it wasn't just some strange random error, it was a personal piece of malice directed at YOU. "The server understood the request, but is refusing to fulfill it": that's an error message with attitude.
The most famous web error message was the "File 404 not found" one, which you got if the page you wanted no longer existed and the webmaster hadn't been bothered to do a redirect or explanation. You still get it now and then but there was a time when you would be more or less guaranteed to get it once a day, and there were some wonderful spoof websites and collections of amusing/dreadful 404 pages.
After half hearted googling have managed to retrieve a page which I think is one of the more amusing spoofs - except it is in what Google Translate thinks is Estonian http://puhkused.com/ Is that right?
[several hours later] Have managed to find ye olde Geek Haiku - ah, this was my favourite:
A File That Big?
A file that big?
It might be very useful.
But now it is gone.