Tax Year Prior to 2020: Is my return being rejected because I'm filing as the surviving spouse?

Maybe. What does the error code say in the message you received?

The Social Security Administration will often freeze the SSN of a deceased person to prevent fraud.  In these cases, you will have to print and mail in your return.

Look up other posts regarding this known problem. 

The only solution to get your federal and state tax returns successfully accepted via E-FILING is at FREETAXUSA dot com.

The only difference in completing tax returns is that FREETAXUSA asks you to input BOTH your state ID and your deceased spouse's state ID numbers/driver's license numbers along with the prior year AGI.   

TurboTax only allows for one person of the joint return's state ID entered in, but because a spouse died, the IRS wants to verify BOTH spouses' ID numbers.  

TurboTax is supposedly aware of this problem, but they shirk fixing their software and ask people to just mail a paper return.  

E-filing is the preferred option for most and customers are willing to pay the fee for getting quick IRS acknowledgement of acceptance of the returns.  

Going to the post office and mailing a paper return is not allowed nor advisable for the 7 million people in the SF Bay Area who are under government-mandated shelter-in-place restrictions because of the high number of Covid19 cases and deaths (and many more unknown cases because of insufficient test kits).  They only allow us to go out for medical reasons and food shopping, and if taking the dog for a walk, we must keep six feet away from any other person.