BSOD meaning: what a Windows blue screen is and what to do about it

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BSOD stands for Blue Screen of Death. It is Windows stopping itself on purpose (Microsoft calls it a bug check or stop error) because carrying on could damage data or security. Write down the stop code and any file name on the screen, remove newly added hardware, then work through drivers, updates, memory and disk checks.

Applies to:Windows 1123H2 and earlier (blue screen), 24H2 and later (black screen)Windows 10
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What it means

BSOD is short for "Blue Screen of Death". It sounds dramatic, but it is only the informal name for what Microsoft calls a bug check, also known as a stop error, stop code error, system crash or kernel error. Windows detected a condition that made it unsafe to keep running, so it halted on purpose. Carrying on could have corrupted data or compromised security.

A blue screen is not one single error. Every crash has its own stop code, such as PAGE_FAULT_IN_NONPAGED_AREA or CRITICAL_PROCESS_DIED, and each code also has a hex value. The screen may name the module that was running, for example AcmeVideo.sys. If Windows is able to save a crash dump, a percent-complete counter appears while it does.

Windows 11 version 24H2 and later show a black screen instead of a blue one, with the stop code and module name. On Windows Insider preview builds the screen can be green. It is the same kind of event in every case.

Because the stop code and any named driver decide the remedy, there is no single fix for all blue screens. This page explains what the screen means and gives a general order to work in.

Symptoms and causes

You are likely dealing with this problem if:

  • The PC restarts or shuts down suddenly with a blue or black error screen.
  • The screen shows a stop code, sometimes a module name ending in .sys, and a percentage while a dump file is written.
  • Crash dumps appear afterwards in %SystemRoot%\Minidump and %SystemRoot%\MEMORY.DMP.
  • Windows crashes again and again in a loop, so you can only get in through Safe Mode.

The usual causes, most common first:

Faulty or incompatible drivers
Microsoft's analysis puts roughly 70-75% of crashes down to third-party driver code. A recently added or updated driver or system service is the classic trigger.
Hardware faults
About 10% of crashes trace to hardware: bad RAM, a failing disk, new or incompatible hardware, or loose cables and expansion boards.
Corrupted system files or file system errors
Damaged Windows files or disk errors can stop the system. Microsoft also lists malware or an MBR infection.
Low disk space, old firmware or missing updates
Having less than 10-15% free disk space, outdated BIOS or UEFI firmware, or missing Windows updates can all contribute.
Unknown
Around 15% of crashes cannot be analysed because memory is too corrupted. Only about 5% are down to Microsoft's own code. An ordinary app such as Notepad is rarely the real cause; it usually just exposes a driver, hardware or OS problem.

How to fix it

Work through these in order. They start with the quickest, safest checks and move to deeper repairs; stop as soon as the problem is gone.

1.Write down the stop code and module name

Easy

The stop code and any named file are the best clues you have, and every later step depends on them.

  1. When the screen appears, photograph it or write down the stop code (for example CRITICAL_PROCESS_DIED) and any file name ending in .sys.
  2. Search for the stop code on its own to find advice for that specific crash.

2.Remove newly added hardware

Easy

New or incompatible hardware is a known trigger, and unplugging it is the quickest test.

  1. Shut the PC down completely.
  2. Disconnect any hardware you added shortly before the crashes started, then restart.
  3. While it is off, check that cables and expansion cards are seated firmly.

3.Start in Safe Mode if Windows will not boot normally

Easy

Safe Mode loads only the basics, which lets you get in and fix things when the crash repeats at every startup.

  1. If you can reach Windows, open the advanced startup menu. On Windows 10 go to Settings > Update & Security > Recovery and under Advanced startup select Restart now. On Windows 11 go to Settings > System > Recovery and select Restart now next to Advanced startup. On either version you can instead hold Shift while selecting Restart from the Start menu.
  2. Choose Troubleshoot > Advanced options > Startup Settings > Restart.
  3. Press 4 or F4 for Safe Mode, or 5 or F5 for Safe Mode with Networking.

4.Check, update or roll back drivers

Moderate

Drivers cause most blue screens, so this is the most likely fix. If the screen named a file, start with the driver it belongs to.

  1. Open Device Manager and look for devices marked with a !.
  2. Open the device (or the one named on the crash screen), then update the driver or roll it back, whichever matches when the problem began.
  3. If the device still causes crashes, disable or uninstall it.

5.Install Windows updates and keep free space

Easy

Missing updates and a nearly full disk are both listed as causes.

  1. Open Windows Update and install everything available, then restart.
  2. Free up space so that 10-15% of the disk stays empty.
  3. If the crashes began right after a particular update, see Windows 11 update error: what the code means and how to fix it for update problems.

6.Look for the crash in Event Viewer

Easy

The log may show a critical error at the crash time that points to the failing component.

  1. Open Event Viewer and go to Windows Logs > System.
  2. Look for critical errors at the time of the blue screen.

7.Use System Restore or another recovery option

ModerateChanges settings

If crashes started after a change, returning to an earlier state can undo it.

Before you start: System Restore can remove programs and drivers installed after the restore point. Save your documents elsewhere first.

  1. Open the recovery tools from Safe Mode or Advanced startup and pick a restore point from before the problems started.

8.Test the memory

Easy

Faulty RAM is a known hardware cause.

  1. Press WinR, run the tool below, and choose to restart and check for problems. Alternatively, search Control Panel for "Diagnose your computer's memory problems".
    Command Prompt
    mdsched.exe
  2. Let the test finish after the restart and note whether it reports any problem. If it does, contact the manufacturer or a repair service.

9.Check system files and the disk

ModerateChanges settings

Corrupted system files and file system errors can both cause stop errors.

Before you start: Disk checks stress a failing drive and can take a long time. Back up important files first.

  1. Open Command Prompt as administrator and check system files.
    Command Promptrun as administrator
    sfc /scannow
  2. Then check the drive for errors: open the drive's Properties > Tools > Check.

10.Scan for malware and check firmware and hardware

ModerateChanges settings

Malware (including MBR infections) and outdated firmware are listed causes, and hardware diagnostics can expose failing parts.

Before you start: Updating BIOS/UEFI firmware carries a risk if power is lost during the update. Follow the manufacturer's instructions exactly and use mains power.

  1. Scan for malware, including the MBR, for example with Microsoft Safety Scanner.
  2. Update BIOS/UEFI firmware using your PC or motherboard maker's instructions.
  3. Run the manufacturer's hardware diagnostics and reseat cards and cables.

11.Analyse the crash dump (advanced)

AdvancedChanges settings

For repeated crashes with no clear cause, the dump file shows which driver was running.

Before you start: Driver Verifier can cause boot loops. Enable it only on a few suspect drivers (10-20 at a time, never all), and use Safe Mode to switch it off if needed, as it cannot run there.

  1. Open Startup and Recovery settings and set Write debugging information to Automatic memory dump.
  2. Open the dump in WinDbg with the symbol path https://msdl.microsoft.com/download/symbols.
  3. Run the analysis command and read the STACK_TEXT section for the faulty module.
    Text
    !analyze -v

Check that it worked

  • The PC runs normally through a restart and a normal working session with no blue or black error screen.
  • No new critical errors appear in Event Viewer under Windows Logs > System.
  • No new dump files appear in %SystemRoot%\Minidump.

If it still fails

  • Make a note of the exact stop code and the module name, because a fix for one code rarely applies to another. Microsoft lists the code-specific advice in its bug check reference.
  • If the screen names a specific code, Microsoft's IT-pro page suggests: DRIVER_IRQL_NOT_LESS_OR_EQUAL (0xD1) update the network driver; KMODE_EXCEPTION_NOT_HANDLED (0x1E) disable or remove the named or newly added driver; NTFS_FILE_SYSTEM (0x24) run disk diagnostics and update the NTFS driver; VIDEO_TDR_TIMEOUT_DETECTED (0x117) and VIDEO_ENGINE_TIMEOUT_DETECTED (0x141) update the display driver; DPC_WATCHDOG_VIOLATION (0x133) find the faulty driver from the dump.
  • If hardware diagnostics report a fault, contact the manufacturer or a qualified repair service rather than continuing to run the PC.

Questions

Is a blue screen a virus?

Not usually. Malware is one possible cause, but Microsoft's analysis puts most crashes down to drivers, with hardware faults next.

Why is my crash screen black instead of blue?

Windows 11 version 24H2 and later show a black screen. It is the same kind of stop error, with the same stop code and module name.

Sources

  1. Troubleshoot blue screen errorsOfficial · Microsoft Support
  2. Bug Checks (Stop Code Errors) - Windows driversOfficial · Microsoft Learn
  3. Stop code error or bug check troubleshooting - Windows ClientOfficial · Microsoft Learn

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