The Dread Error 401 Answered

Hello, whenever I try to publish https://www.instructables.com/id/E8QV5W3HMMF5R3K/ I get an Error 401.
I'm currently trying this from a Linux OS running the Seamonkey browser, but I've also tried it from Firefox in Windows.
I've tried several different Java versions, since that has apparently been seen to be relevant.

...Help?