This is the full message I'm getting:
The Intuit Electronic Filing System is having difficulty recognizing the data in the return you are sending. Make sure your TurboTax program is up-to-date.: Go to the Online menu and select Check for Updates. If you still can't transmit your return, go to www.support.turbotax.com for a solution or workaround. In some cases, you may need to file this return by mail. - Tax Year 2021 transmissions are not available. - ProSeries is not ready to process Tax Year 2021 for this return.
