Microsoft Stop Code (Blue Screen of Death): Complete Troubleshooting Guide for All BSOD Errors

Understanding Microsoft Stop Codes

A Microsoft stop code — colloquially known as the Blue Screen of Death (BSOD), or on Windows 11 occasionally a Green Screen of Death in preview/Insider builds — is Windows' last resort safety mechanism. When the operating system detects a condition so severe it cannot safely continue running (a kernel-mode exception, memory corruption, hardware fault, or critical driver error), it halts everything and displays a stop code.

The blue screen you see contains:

• A frowning face emoji (modern Windows)
• A plain-English description of the error (e.g., KERNEL_SECURITY_CHECK_FAILURE)
• A QR code you can scan with your phone, directing you to https://www.microsoft.com/stopcode for guided help
• A stop code in hexadecimal (e.g., 0xc000021a)
• A percentage counter while Windows collects a memory dump

If you reach this article via the URL on your screen (https://windows.microsoft.com/stopcode or https://www.microsoft.com/stopcode), Windows has already logged a minidump in C:\Windows\Minidump\ that contains detailed crash data.

Most Common Microsoft Stop Codes and Their Causes

1. 0xc000021a / 0xc00021a (Critical Process Died)

This stop code means a critical Windows user-mode process (Winlogon.exe or csrss.exe) failed. It almost always causes a boot loop. Common causes:

• Corrupted system files after a failed Windows Update
• Incompatible third-party software modifying system files
• Registry corruption

2. IRQL_NOT_LESS_OR_EQUAL / DRIVER_IRQL_NOT_LESS_OR_EQUAL

Exact BSOD text: IRQL_NOT_LESS_OR_EQUAL or DRIVER_IRQL_NOT_LESS_OR_EQUAL. A kernel-mode driver attempted to access pageable memory at a process IRQL that was too high. Nearly always a driver bug — network adapters, antivirus kernel components, and GPU drivers are frequent offenders.

3. KERNEL_SECURITY_CHECK_FAILURE

Indicates a kernel data structure violated a security invariant. Caused by outdated or corrupt drivers, hardware failures (especially RAM), or rootkit activity.

4. MEMORY_MANAGEMENT

Points directly at RAM — either a hardware fault in your memory sticks or a driver that is mismanaging memory allocation.

5. BAD_POOL_CALLER

A driver or process made an illegal memory pool request. Common after driver installations or Windows Updates that include driver packages.

6. INACCESSIBLE_BOOT_DEVICE

Windows cannot read the boot partition. Caused by a missing or corrupt storage driver, BIOS/UEFI setting changes (AHCI vs IDE mode), or a damaged SSD/HDD.

Step 1: Capture the Stop Code Information

Before anything else, write down or photograph:

• The stop code text (e.g., KERNEL_SECURITY_CHECK_FAILURE)
• The hex code (e.g., 0x00000139)
• Any file name mentioned (e.g., ntfs.sys, nvlddmkm.sys)

If Windows reboots too fast to read the screen:

1. Press Win + R, type sysdm.cpl, press Enter
2. Go to Advanced → Startup and Recovery → Settings
3. Uncheck Automatically restart under System Failure
4. Click OK

Alternatively, view past crash dumps:

• Open Event Viewer → Windows Logs → System → filter for Critical events
• Use WinDbg (Windows Debugger) to analyze C:\Windows\Minidump\*.dmp files

Step 2: Boot Into Safe Mode or WinRE

If your PC is stuck in a BSOD loop and cannot boot normally:

Method A — Interrupt boot 3 times: Force-power-off your PC during Windows startup three consecutive times. Windows will automatically enter the Windows Recovery Environment (WinRE).

Method B — From Settings (if you can log in): Settings → System → Recovery → Advanced Startup → Restart Now

From WinRE:

• Choose Troubleshoot → Advanced Options → Startup Settings → Restart
• Press 4 for Safe Mode or 5 for Safe Mode with Networking

Step 3: Run System File Checker and DISM

This resolves the majority of 0xc000021a, MEMORY_MANAGEMENT, and random stop codes caused by corrupted system files. Run from an elevated Command Prompt or from WinRE's Command Prompt:

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Restart after both complete, even if SFC reports no violations found.

Step 4: Update or Roll Back Drivers

For IRQL_NOT_LESS_OR_EQUAL, DRIVER_IRQL_NOT_LESS_OR_EQUAL, KERNEL_SECURITY_CHECK_FAILURE, and BAD_POOL_CALLER:

Roll back a recently updated driver:

1. Press Win + X → Device Manager
2. Expand the suspected category (Display adapters, Network adapters, etc.)
3. Right-click the device → Properties → Driver tab → Roll Back Driver

Update drivers:

1. Right-click the device → Update driver → Search automatically
2. Or visit the manufacturer website (NVIDIA, AMD, Intel, Realtek) for the latest driver package

Identify the faulty driver from the minidump: Use the free tool WhoCrashed or WinDbg to read .dmp files and identify the exact .sys file responsible.

Step 5: Check RAM with Windows Memory Diagnostic

For MEMORY_MANAGEMENT, BAD_POOL_CALLER, and random BSODs:

1. Press Win + R, type mdsched.exe, press Enter
2. Choose Restart now and check for problems
3. Windows reboots into the diagnostic tool (runs for ~30-45 minutes)
4. Results appear after restart in Event Viewer under Windows Logs → System (source: MemoryDiagnostics-Results)

If errors are found, test RAM sticks individually (remove one at a time) to identify the faulty module.

Step 6: Run CHKDSK for Disk Errors

For INACCESSIBLE_BOOT_DEVICE and storage-related stop codes:

chkdsk C: /f /r /x

If the drive is in use, schedule for next reboot. From WinRE Command Prompt:

chkdsk C: /f /r

Step 7: Fix 0xc000021a / INACCESSIBLE_BOOT_DEVICE Boot Loops

For stop codes that prevent Windows from booting, use WinRE Command Prompt:

bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd

If bootrec /fixboot returns "Access is denied," first run:

bcdboot C:\Windows /s C: /f ALL

Then retry bootrec commands.

Step 8: Microsoft Surface-Specific BSOD Fixes

Blue screens on Microsoft Surface (Surface Pro, Surface Laptop, Surface Book) are often caused by:

• Outdated Surface firmware — update via Windows Update → Optional Updates → Driver and firmware updates
• Incompatible Type Cover or docking station driver
• Touch or pen driver conflicts

Visit Device Manager → Firmware and ensure Surface UEFI firmware is current. For Surface blue screen issues, Microsoft provides the Surface Diagnostic Toolkit for Business as a free download from the Microsoft Download Center.

Step 9: Investigate Microsoft Teams or Application-Specific BSODs

If BSODs occur specifically when launching Microsoft Teams, video conferencing apps, or during gaming:

• These are almost always GPU driver crashes (nvlddmkm.sys for NVIDIA, atikmpag.sys for AMD)
• Update GPU drivers to the latest Game Ready or Studio release
• Disable hardware acceleration in Teams: Teams → Settings → General → uncheck "GPU hardware acceleration"
• Check for conflicting antivirus kernel modules (temporarily disable and test)

Step 10: Last Resort — Reset or Reinstall Windows

If all above steps fail:

Option A — Reset this PC (keeps files): Settings → System → Recovery → Reset this PC → Keep my files

Option B — Clean install: Download the Windows 11 Media Creation Tool or Windows 10 Media Creation Tool from microsoft.com, create bootable USB, and perform a clean installation.

Before resetting: Back up important files to an external drive or cloud storage. A Reset or Reinstall will remove installed applications.