Guys this may be a real easy quick fix for this problem. So I struggled for several days on this issue. I use TurboTax on a MacBook pro using Firefox as my browser. Stuck in the same endless loop that everybody else was username is correct password is correct but not doing anything past that always giving me an error. So
Then I simply looked up how to enable third-party sharing on my e-trade account. Go into your profile security settings and manage that. While third party sharing was already enabled which doesn't explain why the error occurred I just hit save again and exited then tried to import into TurboTax again and it worked!
Hopefully this is the fastest easiest fix ever for you guys who are having the same issue.
