I have been having the same issue with my QBSE login. I have used Chrome for two years with QBSE and no issues. I recently added QB Online for a second company, which is a corporation, but these have different logins and are indeed different products. My QB Online has no issues for logging in, but the QBSE for the past month has given me this HTTP 400-Bad Request every time I have tried to login. Even worse, I tried calling the QB Support number [phone number removed], which is useless as no matter the selection you make from the phone tree it hangs up on you. This needs to get fixed and in a hurry.
