It's not clear exactly what you are doing. You cannot open a .tax2023 file in the 2024 software.
Are you starting the 2024 software by double-clicking a .tax2024 file in Windows? Don't do that. Start the 2024 TurboTax program by double-clicking the desktop icon (or by clicking on it in the Windows Start menu). Then start a new return. On the first screen when you start a new return, click "Transfer Return" for the 2023 file that you want to transfer from.
You cannot transfer into a 2024 tax return that is already started, or into an existing .tax2024 file. You can only transfer when you first start a new return.
