I had issues opening Turbotax 2020 and 2021 in Windows 10 (21H2 OS Build 19044.1415) .
Event Viewer had a .NET error on C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll.
.NET repair tool did not fix the problem.
I replaced the clr.dll v4.8.4420.0 with on old one from another computer v4.8.4400.0, and Turbotax opened again.
Not sure which Windows update pushed the new DLL, but it broke Turbotax.
