Redirect to upgrade.php, no database update required (after upgrade to 3.2)

I recently moved one of our blogs from a linux box over to a Windows one. After I moved it I noticed that the 3.2 upgrade was available, so ran the automatic upgrade as I usually do. It went smoothly, then when I finished it asked me to upgrade the database, which it did, then let me back in to the admin panel.

An hour or so later I suddenly got a problem whereby when I tried to browse to /wp-admin, I would be taken straight to /wp-admin/upgrade.php?_wp_http_referer=%2Fwp-admin%2F. I disabled all plugins, reset the them, and more, but it still didn’t work. I put

echo 'STOP!';
exit;

at the very start of /wp-admin/index.php, and it still did the redirect. This is when I started wondering that it was weird…

I deleted my cookies, and still it happened. I closed Firefox down and opened it again a few times, and it still didn’t work. My colleagues by now could get on fine, and I could with other browsers, so I was happy it wasn’t anything to do with plugins, themes, etc.

Eventually I cleared my cache, and it worked. So, this is more of a note to people with the same problem than asking for help, to make sure you clear your cache when you run an upgrade.

Hope that helps someone!