Just to let everyone know who might have similar problems after the switch to 0.18 I was unable to login with the account I had even after clearing cache on multiple apps and trying a different browser. A password reset fixed it, so if anyone else is having the problem, this might be your fix.
I had the same problem. Both on jerba and web browser. I kept getting 404. An hour or two later I was able to login. I don’t know what happened. But I didn’t have to reset password.