The solution from @jkmizz and @blubegone91 on 5/10/21 worked for me as well!
I bought a CD of Turbo Tax Deluxe for the 2020 Tax Year and installed it on a mac laptop computer. When I tried to efile my federal taxes, I got the error message "Your Transmission Didn't Go Through", "Validation failed: There is an update available for your program. Before you can e-file, you'll need to get this update." I tried everything that others have mentioned to update it, but I kept getting the same error message.
Then I tried what jkmizz and blubegone91 suggested, and it worked! I unplugged my router's power cord to turn it off; de-attached the Ethernet cable that connected my modem and router; unplugged my modem's power cord; re-plugged it in to reboot it; connected my laptop to my modem via the Ethernet cable (I had to use a USB 3.0 to Gigabit Ethernet Adapter since my laptop does not have an Ethernet port). Once that was successfully connected, when I started Turbo Tax, there was a new update to download. After installing the update, I was able to efile my federal taxes.
