Can you provide more details please. What exactly is "the upgrade link"?

There's a button to upgrade, but it doesn't take you to our site.
There's a link to the news post.

I can't find any error in our log or work out how this could happen.

And it's bizarre as it's trying to generate an upgrade from RC33 to RC29.

Oh, I think you mean the personal upgrader link, deep within upgrader.php?

(Click to enlarge)

The button on the upgrader link shown on Admin Dashboard is what I hit originally, then I think I might have clicked "generate a personalised manual upgrader" and it took me to that erroneous URL.

I did reproduce and fix eventually, but to do it you had to click that button, login to the upgrader, go to the file transfer step, then click the link to generate a personal upgrader.

Yeah, that's right. I actually thought that was the correct thing to do given the link to the news post wasn't there and that was. Sorry for my halfarsed reporting.