How frustrating. You have my sympathy. So by PC I assume you mean Windows 10? While Windows System Restore is not enabled by default on Windows 10 it will still work. Have you considered trying to regress to an earlier restore point? Do you have any tools for checking the Windows registry for errors? Is there another PC for you to try (it's my understanding that you are able to install and activate one copy of TTAX with the same program key on more than one PC). Had you already loaded one, or more?, state programs before hitting this error? Did TTAX support provide you with a different activation key to try? Is your internet connection via WiFi or cable connection to your router/cable-modem and have you tried varying how you connect and/or resetting-rebooting your router/cable-modem? Did TTAX support explain how program activation uses the key? Is there an Inuit server somewhere which the program on your PC must reach to check/register the program key when activating? I've been using TTAX since the mid-1990s, spanning many versions of Microsoft OS, but don't recall any earlier versions that required an activation key. Is it your understanding that this is new for the 2019 tax year? Lastly, while you've probably already spent too many hours on this and exhausted your tolerance for Googling, this problem apparently is also discussed on this thread.
https://ttlc.intuit.com/community/taxes/discussion/re-my-security-code-to-activate-my-2019-software-...
