Microsoft released a fix to the original issue (see below for description) that occurred after installing updates. If you check for updates today, you’ll see the following update under the “optional quality update available” section:
2021-03 Cumulative Update for Windows 10 Version 20H2 for x64-based Systems (KB5001567)
If you had previously installed the updates and were experiencing issues with TaxCycle, we encourage you to install this latest update to solve this issue. For everyone else, you may choose to install the update now or wait until Microsoft includes it in a required update.
For more details, see
We’re receiving reports that Windows 10 March 2021 cumulative updates are causing issues for some people running TaxCycle.
When starting TaxCycle after installing the updates, people report a system crash with a “blue screen of death” displaying “APC_INDEX_MISMATCH” stop error code. This occurs when TaxCycle attempts to detect the installed printers when it starts.
While there is a way to fix this issue, it requires entering commands on the command prompt. See Microsoft shares fix for Windows 10 BSOD error “APC_INDEX_MISMATCH” (windowslatest.com).
For a more user-friendly fix, you can also attempt to roll back the affected updates through the Update History in Windows. See Remove an installed Windows update. If you choose this, we strongly recommend backing up your system first.