Big news for anyone else still monitoring this thread. I was just able to e-File my amended federal return (with foreign tax credit) successfully. I'll report back after 24-48 hours when I hear if my return was accepted.
This was somewhat surprising since it came after getting a warning page that e-Filing was closed for the season on October 17. Perhaps that's not applicable to amended returns. I filed my amended CA state return long ago, and also made an electronic payment of the amount from my federal amended return. Since the deadline for actually filing the amended return is long (there won't be late payment fees on a payment already made), I've been holding out to see if the issue would be fixed by the system upgrade mentioned elsewhere in this thread. I've been retrying every 1-2 weeks with the same error until today, so it seems the upgrade may've finally occurred.
Here's hoping I learn my is accepted and this saga is actually over, rather than finding out that this submission was the result of a different bug.
