Was trying to install TurboTax 2021 Premier on Mac OS 10.15 - supposedly a supported platform. I tried all the fixes, disabling my virus protection, opening firewall etc. Also tried from a CD as well as downloads. Finally gave up and tried H&R Block - this also did not work, almost same results. Got a refund on that and downloaded TurboTax Premier 2021 to our Dell laptop/Windows 10 and it appears to work fine. Was able to move my Mac TurboTax returns over to the Dell and all info was captured for this year's return. This is obviously a problem with Mac OS Catalina 10.15. I opened a problem with the Mac Community forum, but will probably not open a ticket with Apple as I've burned enough hours fooling with this anyway. Thanks.
