Since today, I haven't been able to sign in to iCloud.com with my personal account. The site shows a red "(!) Fallback" message after I try to log in. I cleared cookies, tried several browsers and devices—including a PC, iPhone, and MacBook—and even reset my password, but nothing helped. Apple Support wasn't able to identify the issue. My business account logs in normally, so the problem seems limited to my personal account. It eventually started working again, which makes me think there may have been a temporary service problem. Has anyone else run into this?
2 Answers
I’ve seen the same behavior after entering the verification code: the code is accepted, but the browser never finishes signing in and shows the fallback message. Clearing cookies and site data, then restarting the browser, is worth trying, but if it happens everywhere, the issue is likely on Apple’s end.
That message sounds more like a temporary account or service-side issue than a bad password. Since another account works and the problem appeared across multiple devices, there probably wasn’t anything wrong with your browser. Waiting a while and trying again may be all that’s needed.
That seems to have been the case—it eventually fixed itself, so Apple may have been having a temporary outage.

I had already tried clearing cookies, but luckily it started working again on its own.