I'm using a Dell Inspiron 3593 running Windows 11. A few days ago, I tried installing a preview update, but it didn't complete successfully. Since then, Windows shows Stop Code 0xc000021a. I can reach the sign-in screen and see its background normally, but after signing in the desktop is black. The mouse cursor and Task Manager are still available. I also tried opening the Windows Recovery Environment during startup, but it gets stuck on the message saying the device encountered a problem and needs to restart instead of actually restarting. I'm worried about reinstalling Windows because my files are not backed up. What recovery steps can I try to repair Windows or remove the failed update without losing my data?
2 Answers
A clean reinstall may fix the problem, but it should be a last resort since the files are not backed up. Try accessing Task Manager with Ctrl+Shift+Esc and use File > Run new task to launch tools such as Explorer or an elevated Command Prompt. From there, you may be able to copy important files to an external drive or run Windows repair commands before considering a reset. If Windows Recovery remains inaccessible, booting from a Windows installation USB can provide repair options without immediately erasing the internal drive.
This error usually means a critical Windows user-mode process failed, often because of a damaged update, corrupted system files, a driver, or software that modified core Windows components. Before trying repairs, shut the laptop down completely and disconnect nonessential USB devices such as external drives, docks, printers, controllers, and USB network adapters. Leave only the display, keyboard, mouse, and power connected, then try starting it again. If the problem began immediately after the preview update, removing that update should be one of the first recovery steps.

I haven’t seen another blue-screen message, and I still can’t get into Safe Mode or the recovery options. I’m mainly trying to protect my files before attempting a reinstall.