BSOD Stop Code Lookup: Meaning and Causes
Type the stop code from your blue screen in any form (0x1A, 1a or MEMORY_MANAGEMENT) to see what it means, common causes and what to check first.
Results show up here as you type. Enter the code as it appears on your screen.
No name matched, so these come from the descriptions.
Blue screen stop code list
34 stop codes people run into most. Open a code to see its causes and what to check.
0x0000000AIRQL_NOT_LESS_OR_EQUAL
Windows or a driver accessed memory at an invalid address.Common causes
It usually follows installing a faulty driver, system service or BIOS. During a Windows upgrade, an incompatible driver, antivirus or backup tool may be the cause.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Remove or roll back drivers and programs you installed or updated recently
- Temporarily turn off antivirus or other tools that constantly monitor the disk
- Remove hardware you added recently and confirm it is compatible with your Windows
0x00000019BAD_POOL_HEADER
A pool header in kernel memory is corrupted.Common causes
A driver mishandling memory can cause it. If it shows up only now and then, faulty RAM is a possibility.
Check first
- Remove or roll back drivers and programs you installed or updated recently
- Test your RAM with Windows Memory Diagnostic
- Look for errors at the same time in the Event Viewer System log
0x0000001AMEMORY_MANAGEMENT
A severe memory management error occurred.Common causes
It can point to a problem with physical memory (RAM), so a memory test is a good first step.
Check first
- Test your RAM with Windows Memory Diagnostic
- Remove or roll back drivers and programs you installed or updated recently
- Look for errors at the same time in the Event Viewer System log
0x0000001EKMODE_EXCEPTION_NOT_HANDLED
A kernel-mode program, such as a driver, raised an exception that was not handled.Common causes
A faulty driver or system service is a common cause. Hardware issues such as BIOS incompatibility or memory conflicts can also trigger it.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Remove or roll back drivers and programs you installed or updated recently
- Test your RAM with Windows Memory Diagnostic
- Check for BIOS (UEFI) and firmware updates from the maker
0x00000024NTFS_FILE_SYSTEM
A problem occurred in ntfs.sys, the driver that reads and writes NTFS drives.Common causes
Disk corruption (a damaged NTFS file system or bad sectors) or a corrupted storage driver can cause it.
Check first
- Scan for disk errors and bad sectors with chkdsk /f /r
- Look for errors at the same time in the Event Viewer System log
- Keep 10-15% of the drive free
- Repair corrupted system files with sfc /scannow
0x0000003BSYSTEM_SERVICE_EXCEPTION
An exception happened while switching from non-privileged code to privileged code.Common causes
Accessing an invalid memory address can cause it. If the responsible driver is known, its name appears on the screen.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Update drivers for any device marked with ! in Device Manager
- Look for errors at the same time in the Event Viewer System log
- Repair corrupted system files with sfc /scannow
0x0000004EPFN_LIST_CORRUPT
The page frame number (PFN) list is corrupted.Common causes
It is usually caused by a driver passing bad memory information.
Check first
- Remove or roll back drivers and programs you installed or updated recently
- Update drivers for any device marked with ! in Device Manager
- Look for errors at the same time in the Event Viewer System log
0x00000050PAGE_FAULT_IN_NONPAGED_AREA
Invalid system memory was referenced, such as a wrong address or memory already freed.Common causes
A faulty driver or system service, antivirus software, a corrupted NTFS volume or defective RAM (including video memory) can cause it.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Temporarily turn off antivirus or other tools that constantly monitor the disk
- Scan for disk errors and bad sectors with chkdsk /f /r
- Test your RAM with Windows Memory Diagnostic
0x00000077KERNEL_STACK_INPAGE_ERROR
Kernel data could not be read from the paging file into memory.Common causes
Bad disk sectors, loose or faulty cables and RAM errors are common causes. A virus can also cause it.
Check first
- Scan for disk errors and bad sectors with chkdsk /f /r
- Check storage cables and connections
- Test your RAM with Windows Memory Diagnostic
- Look for errors at the same time in the Event Viewer System log
0x0000007AKERNEL_DATA_INPAGE_ERROR
Kernel data could not be read from the paging file into memory.Common causes
Bad sectors and cable problems are common. Failing storage, failing RAM or a virus can also cause it.
Check first
- Scan for disk errors and bad sectors with chkdsk /f /r
- Check storage cables and connections
- Test your RAM with Windows Memory Diagnostic
- Run a virus scan with up-to-date antivirus
0x0000007BINACCESSIBLE_BOOT_DEVICE
Windows lost access to the system partition during startup.Common causes
A failing boot disk, repartitioning, changed BIOS settings, a new disk controller or incompatible storage hardware can cause it.
Check first
- Undo recent BIOS (UEFI) changes, such as the storage controller mode
- Remove hardware you added recently and confirm it is compatible with your Windows
- Boot into safe mode, then restart normally
- Check for BIOS (UEFI) and firmware updates from the maker
0x0000007ESYSTEM_THREAD_EXCEPTION_NOT_HANDLED
A system thread raised an exception that was not handled.Common causes
A driver problem, hardware incompatibility or a memory conflict can cause it.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Look for errors at the same time in the Event Viewer System log
- Check for BIOS (UEFI) and firmware updates from the maker
- Remove hardware you added recently and confirm it is compatible with your Windows
0x0000007FUNEXPECTED_KERNEL_MODE_TRAP
The CPU raised a trap that the kernel failed to catch.Common causes
It typically follows installing faulty or mismatched hardware (especially RAM) or a hardware failure. Overclocking can also cause it.
Check first
- Remove hardware you added recently and confirm it is compatible with your Windows
- Test your RAM with Windows Memory Diagnostic
- If you overclocked, go back to default clocks
- Look for errors at the same time in the Event Viewer System log
0x0000009FDRIVER_POWER_STATE_FAILURE
A driver is in an inconsistent or invalid power state.Common causes
Driver problems when the PC enters or wakes from sleep or hibernation can cause it.
Check first
- Remove or roll back drivers and programs you installed or updated recently
- Update drivers for any device marked with ! in Device Manager
- Temporarily turn off power saving in Power Options
- Look for errors at the same time in the Event Viewer System log
0x000000A5ACPI_BIOS_ERROR
The PC's ACPI BIOS is not fully compliant with the ACPI specification.Common causes
It is a BIOS-side problem, so a newer BIOS is needed.
Check first
- Check for BIOS (UEFI) and firmware updates from the maker
0x000000BEATTEMPTED_WRITE_TO_READONLY_MEMORY
A driver tried to write to read-only memory.Common causes
It is a driver problem. If the responsible driver is known, its name appears on the screen.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Remove or roll back drivers and programs you installed or updated recently
- Update drivers for any device marked with ! in Device Manager
0x000000C2BAD_POOL_CALLER
The current thread made a bad pool request.Common causes
It happens when a driver makes an invalid request, such as freeing the same memory twice. Faulty RAM is also possible.
Check first
- Remove or roll back drivers and programs you installed or updated recently
- Test your RAM with Windows Memory Diagnostic
- Update drivers for any device marked with ! in Device Manager
0x000000C4DRIVER_VERIFIER_DETECTED_VIOLATION
Driver Verifier caught a fatal error in a driver.Common causes
It only appears when Driver Verifier has been turned on.
Check first
- If you turned on Driver Verifier, turn it off
- If a driver (.sys) is named on the screen, update or disable that driver
0x000000D1DRIVER_IRQL_NOT_LESS_OR_EQUAL
A kernel-mode driver accessed pageable memory at too high an IRQL.Common causes
It is usually a driver using an improper memory address. An outdated network driver is also a known cause.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Update your network driver
- Remove or roll back drivers and programs you installed or updated recently
- Look for errors at the same time in the Event Viewer System log
0x000000EATHREAD_STUCK_IN_DEVICE_DRIVER
A thread in a device driver is spinning endlessly.Common causes
It is often stuck waiting for hardware to go idle. A bad graphics card or display driver is a frequent cause.
Check first
- Update your graphics driver to the latest version
- Remove hardware you added recently and confirm it is compatible with your Windows
- Look for errors at the same time in the Event Viewer System log
0x000000EDUNMOUNTABLE_BOOT_VOLUME
The boot volume could not be mounted.Common causes
It is typically related to a failing boot storage device such as a hard drive.
Check first
- Run Startup Repair from the Windows Recovery Environment
- Scan for disk errors and bad sectors with chkdsk /f /r
- Run the PC or drive maker's hardware diagnostics
0x000000EFCRITICAL_PROCESS_DIED
A critical system process (such as csrss.exe or winlogon.exe) ended.Common causes
It happens when that process is corrupted. To narrow it down, start with system files and recently changed drivers or hardware.
Check first
- Repair corrupted system files with sfc /scannow
- Remove or roll back drivers and programs you installed or updated recently
- Update drivers for any device marked with ! in Device Manager
- Look for errors at the same time in the Event Viewer System log
0x000000F4CRITICAL_OBJECT_TERMINATION
A process or thread crucial to the system exited or was terminated unexpectedly.Common causes
Once such a process ends for any reason, the system cannot keep running. Narrow it down with the basic checks.
Check first
- Look for errors at the same time in the Event Viewer System log
- Remove or roll back drivers and programs you installed or updated recently
- Repair corrupted system files with sfc /scannow
0x000000FCATTEMPTED_EXECUTE_OF_NOEXECUTE_MEMORY
An attempt was made to execute non-executable memory.Common causes
When possible, the driver that tried to run that memory is named on the screen.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Remove or roll back drivers and programs you installed or updated recently
0x00000101CLOCK_WATCHDOG_TIMEOUT
A secondary processor did not receive an expected clock interrupt in time.Common causes
It typically happens when a processor is unresponsive or deadlocked.
Check first
- Check for BIOS (UEFI) and firmware updates from the maker
- Remove or roll back drivers and programs you installed or updated recently
- Run the PC or drive maker's hardware diagnostics
- Look for errors at the same time in the Event Viewer System log
0x00000109CRITICAL_STRUCTURE_CORRUPTION
The kernel detected corruption of critical kernel code or data.Common causes
Either a driver modified kernel code or data, or hardware such as failing memory corrupted it.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Test your RAM with Windows Memory Diagnostic
- Look for errors at the same time in the Event Viewer System log
- Run the PC or drive maker's hardware diagnostics
0x00000116VIDEO_TDR_FAILURE
Resetting the display driver to recover from a timeout failed.Common causes
It mostly happens under heavy graphics load such as gaming. An outdated graphics driver, overclocking, poor cooling or power, or defective parts can cause it.
Check first
- Update your graphics driver to the latest version
- If you overclocked, go back to default clocks
- Check that fans, cooling and power supply are adequate
- Close background programs while gaming
0x00000119VIDEO_SCHEDULER_INTERNAL_ERROR
The video scheduler detected a fatal violation.Common causes
The faulting module is sometimes the graphics (video) driver.
Check first
- Update your graphics driver to the latest version
- Look for errors at the same time in the Event Viewer System log
0x00000124WHEA_UNCORRECTABLE_ERROR
A fatal hardware error occurred, reported through WHEA.Common causes
It is typically a physical hardware failure: heat, or defective parts such as memory or the CPU. A driver is a less likely cause.
Check first
- If you overclocked, go back to default clocks
- Check that fans, cooling and power supply are adequate
- Test your RAM with Windows Memory Diagnostic
- Run the PC or drive maker's hardware diagnostics
0x0000012BFAULTY_HARDWARE_CORRUPTED_PAGE
The memory manager detected corruption caused through physical memory access.Common causes
Defective RAM, or a device, driver or firmware wrongly modifying physical memory, causes it.
Check first
- Test your RAM with Windows Memory Diagnostic
- Remove or roll back drivers and programs you installed or updated recently
0x00000133DPC_WATCHDOG_VIOLATION
A deferred procedure call (DPC) ran too long, or the system stayed at a high IRQL for too long.Common causes
It is caused by a faulty driver that does not finish its work in the allowed time.
Check first
- If a driver (.sys) is named on the screen, update or disable that driver
- Look for errors at the same time in the Event Viewer System log
- Remove hardware you added recently and confirm it is compatible with your Windows
- Remove or roll back drivers and programs you installed or updated recently
0x00000139KERNEL_SECURITY_CHECK_FAILURE
The kernel detected corruption of a critical data structure.Common causes
It is usually a driver mishandling kernel data.
Check first
- Update drivers for any device marked with ! in Device Manager
- Look for errors at the same time in the Event Viewer System log
- Remove or roll back drivers and programs you installed or updated recently
0x00000154UNEXPECTED_STORE_EXCEPTION
The kernel memory store component caught an unexpected exception.Common causes
There is no single known cause, so work through memory, drivers and system files first.
Check first
- Look for errors at the same time in the Event Viewer System log
- Test your RAM with Windows Memory Diagnostic
- Update drivers for any device marked with ! in Device Manager
- Repair corrupted system files with sfc /scannow
0xC000021AWINLOGON_FATAL_ERROR
The Winlogon process ended unexpectedly.Common causes
It happens when a user-mode subsystem such as Winlogon or CSRSS is compromised. Newly installed third-party apps or drivers, or mismatched system files after restoring a backup, are common causes.
Check first
- Remove or roll back drivers and programs you installed or updated recently
- Repair corrupted system files with sfc /scannow
- Look for errors at the same time in the Event Viewer System log
How to find your stop code
- Bottom of the blue screenThe stop code, such as MEMORY_MANAGEMENT, is shown here. If the faulting module is known, its name (a .sys file) appears too.
- Windows 11 24H2 and laterThe screen color and message changed, so it can appear as a black screen. The stop code and module name are still shown.
- Event ViewerPress Win+R, enter eventvwr.msc, and open the bug check event in the System log at the time of the crash to see the stop code details.
- Dump filesSmall dumps are saved in %SystemRoot%\Minidump and the rest in %SystemRoot%\MEMORY.DMP. Reading them takes a debugger such as WinDbg.
Most blue screens come from drivers
About 70% of Windows crashes come from third-party drivers and about 10% from hardware. Whatever the code, start with drivers and devices you changed recently.
Basic checks when blue screens keep coming back
A one-off blue screen is usually fixed by the restart. If the same code keeps restarting your PC, go through these steps.
- Remove new hardwareIf you added hardware before the error, shut down, remove it and restart.
- Start in safe modeIf the PC will not restart normally, start in safe mode and do the remaining steps from there.
- Check Device ManagerRight-click Start, open Device Manager and update the driver of any device marked with an exclamation point (!).
- Free up spaceKeep 10-15% of your drive free.
- Windows UpdateGo to Start > Settings > Windows Update and select Check for updates.
- Restore WindowsIf nothing helps, roll back with a system restore point or another recovery option.
How often has it crashed?
Lutimize (our app) runs a System Check that counts blue screen dumps from the last 30 days with the latest time, lists devices with driver problems and runs SFC. It does not analyze stop codes.
Common questions
I got one blue screen. Do I need to fix something?
Usually the restart fixes it and nothing else is needed. Check things only if the same stop code keeps restarting your PC.
Are a stop code and an error code the same thing?
Yes. Each stop code has a name (MEMORY_MANAGEMENT) and a hex value (0x0000001A), and either one finds the same code.
My screen was black, not blue. Is it the same?
From Windows 11 24H2 the same error can show on a black screen. A blank black screen with no stop code, or just a cursor, is a different problem.
What if my code is not on the list?
This page covers the 34 most common codes. For other codes, start with the basic checks.
Can a stop code alone tell me the exact cause?
No. One code can have several causes, so pinning it down takes analyzing the dump file with a debugger (WinDbg).
Is my search sent anywhere?
No. Searching happens only in this browser, and what you type is never sent to a server or added to the address.
FPS Drop and Stutter Cause Checker Check My PC Specs PSU Calculator
Last reviewed 2026-11-12