Its means that the extension form to e-file is not yet available, see links in my original answer.  You can print the form out in the program & mail it in.

How do I file an IRS extension (Form 4868) in TurboTax Online?

https://ttlc.intuit.com/community/extensions/help/how-do-i-file-an-irs-extension-form-4868-in-turbot...