My friend also encountered this problem when they tried to log into the devforum using their roblox account.
I’m always logged in on my pc, but I wanted to see if the problem is on their end or if something’s up with the website. So, I simply opened a new incognito tab, logged into my roblox account (from roblox.com), then tried logging into the devforum from another incognito tab and it gave me this error:
Bad Request
400 | There was a problem with your request
Apparently, I can’t even paste a picture here onto this post for some reason. It says: Sorry, there was an error uploading that file. Please try again.
This might also be related to @OopsIStubbedMyToe’s post.