If my my 2019 Federal Tax Return Summary show my Adjusted Gross Income as 10499.00 but it is being rejected. We filed joint but my husband passed away March 27, 2020.

Both you and your husband's AGI should be the same. The AGI on the 2019 Form 1040 is line 8b.

Tax Expert @DeanM15 says the IRS says that the surviving spouse may file a Married Filing Jointly return by e-filing, but in practice, many surviving spouses must file by mailing in even if they have the AGI correct. 

You can read more here.