Upvote doesn't work if it is the very first thing tried

[cwjohan]

If a dyno has just been started/restarted and the very first thing the user does is to click an upvote button, the upvote fails.

Once a document has been added, the upvote works reliably.

If multiple users attempt an upvote initially and keep trying, the upvote eventually starts working (after a couple tries?).

Especially in Internet Explorer, there is a delay before one see the upvote result and it may appear to have failed when it actually worked. If one tails the log, one can see which attempts actually fail.