What makes you think it is keychain related?
if you get the message "TurboTax cannot be opened because Apple cannot check it for malicious software" then that is caused by the Apple "Gatekeeper" introduced with OS X 10.15 (Catalina).
That has nothing to do with TurboTax and will happen for any application not purchased from the Apple Store.
See this Apple article on this: https://support.apple.com/en-us/HT202491
And this TurboTax help article: https://ttlc.intuit.com/community/troubleshooting/help/turbotax-for-mac-won-t-open-when-installed/00...
For older Mac systems when TurboTax will not open.
Be sure that System Preferences -> Security & Privacy -> General -> Allow apps downloaded from App Store and identified developers is checked.
Go to the Applications folder and select the TurboTax application in the Finder and right click with the mouse (or control click) ans select the top "open". That should force the first open. After that it should open normally.
I am having the same issue. I'm on Big Sur and after the update to TurboTax 2020 home and business I cannot get the app to load. It starts to open, but the when the checking for updates window comes up, the program crashes.
You may need to remove and reinstall TurboTax on your Mac. Please follow the instructions below to remove and reinstall.
Please follow these instructions for the administrative rights you may need to remove TurboTax.
If you have any trouble reopening it after reinstallation, please follow these steps.
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Here is what finally resolved the issue after spending 1 hour on the phone with TuboTax tech support.
Please follow the steps below:
Open your User/Library folder. In the Finder when you click on the "Go" menu and Hold Option key you can click on Library. Or, click on "Go to Folder" and in the box put "~/Library" In the Library folder look for the "Preferences" folder. Open it.
In the Preferences folder look for file: "com.intuit.turbotax.2020.plist" Throw that file in the Trash. Then reboot your Mac. (Shutdown/Restart) After your Mac starts up you can open your TurboTax 2020 tax file. The file is normally saved in your Mac Documents folder. The file is probably named "Your Name 20.tax2020" When TTX launches DO NOT CLICK anything until you read Part B next!... --------------------------------
Part B If you open TTX and see the "It looks like we hit a snag" box. Do NOT CLICK "send to TurboTax". Click the little red close button in top left of box. You might have other windows in front you need to close first like Check for Updates, Welcome, Register Later... Just make sure you DO NOT click "Send to TurboTax". (If you did click "Send to TurboTax" and your it crashes, go back to Part A) Now, if your tax file is open and you had a problem with E-File... (As others have suggested) You might want to try to first E-File ONLY the Federal return without the State. It maybe safer to just get the Fed filing out of the way since it doesn't need a payment. The payment section is often what is causing the crash. If you got the Federal E-File done you can go back to your File a Return section of TTX and do just the State E-File. If you already entered your payment for State E-file you should see the "We've restored all products..." Do NOT CLICK the big blue "Close" button. Click the little white "Close" button in bottom right corner.