Same thing just happened to me — given the jank and bugs I find in TurboTax every year, my bet is that TT is f**king this up somehow..
Edit: To be explicit, I filed for an extension with TT since I'm missing a form for 2023 taxes, and got back this error: "R0000-902-01 - Taxpayer TIN in the Return Header must not be the same as a TIN of a previously accepted electronic return for the return type and tax period indicated in the tax return." — I wonder if TT is doubling filing extensions or something..
