ORDER LINK - https://we.tl/t-mt8rmgp7zV
DESTRO LINK - https://we.tl/t-bUFmcshomq
For those of us who sit in the Discord awaiting updates when the server is down, @Davjen has found a workaround for this issue with the launcher.
You will need to re-download the data.mvp file from the above links, and replace with the one in your current directory.
This should allow you to login through the launcher.
If this doesn't work, the second option is to redownload the game files through the torrent listed in the guide here: viewtopic.php?f=4&t=31241
As wargrimnir has said, this is a temporary solution and the team are working on a fix. If you want to wait, before downloading files etc, that's fine

If you want to thank Davjen, check out his stream here - https://www.twitch.tv/davjen
Edit: I have added two separate links from confirmed players on both Order and Destruction. The initial file still works, but just for re-assurance there are now two links to data.myp files from working clients of an Order player, and a Destruction player.