502 - Web server received an invalid response while acting as a gateway or proxy server

A lot of people are getting this error when registering on https://register.guildwars2.com/ with the BWE #3 keys.

502 - Web server received an invalid response while acting as a gateway or proxy server.

There is a problem with the page you are looking for, and it cannot be displayed. When the Web server (while acting as a gateway or proxy) contacted the upstream content server, it received an invalid response from the content server.

I thought this was already fixed.