Where is the error when electronic filing fails? The email says "Once you've opened your return in TurboTax, the details about what needs updating will be displayed."

this is a public forum. we can't see your return so we really  can't be sure of the issue

suggestions

1) if you used "various" for date paid or accrued try 12/31/2020

2) from another user

I'm using TT Online. My solution was to delete my 1116 using these instructions, then request the 1116  interview again: 

- Federal / Deductions and Credits / Estimates and Other Taxes Paid / Foreign Tax Credit / Revisit.

3) if your FTC is less than $300 single or $600 married filing jointly try the simplified method - no 1116 required

delete the 1116 see link above

on 1099-div only enter the amount of FTC in box 7 and use various for the country. don't use any other box for lines 7 or 8

4) contact support