How Do You Fix A C000021a Fatal System Error?
If you attempt to install a piece of hardware or software on your PC computer that is incompatible with your system, you may see a blue screen with a C000021a fatal error warning. The easiest way to recover the Windows operating system from this type of error is to restore your computer to a previously working state. Step 1 Open the Start menu and click on the “Shut Down” button. Step 2 Choose the “Restart” button from the drop-down menu and click “OK.” The computer will now safely shut down and begin the rebooting process. Step 3 Press the “F8” key on your keyboard when prompted during the boot process. Step 4 Use the up-and-down arrow keys to highlight the “Last Known Good Configuration” option. Then hit “Enter.” Step 5 Use the up-and-down arrow keys to highlight the operating system version that you wish to boot up to, and then hit “Enter” again. The system will now restart to the last working version of your operating system, which will eliminate the C000021a fatal error.
