What KMODE_EXCEPTION_NOT_HANDLED means
Windows stops when kernel-mode code raises an exception nothing can handle. A faulty or incompatible driver or low-level utility is the typical cause, and unstable memory or overclocking can produce the same symptom.
Common causes
- A faulty or incompatible driver or low-level utility
- Corrupted system files
- RAM errors
- Overclocking or undervolting instability
How to fix KMODE_EXCEPTION_NOT_HANDLED
Work through these in order and test after each one. Stopping as soon as the crashes stop tells you which change mattered.
- Note the file name on the blue screen. If the screen shows a line such as "What failed" followed by a .sys file, write it down. Searching that file name shows which driver it belongs to, which tells you what to update or remove. The named file is the code that crashed, which is not always the root cause.
- Undo the most recent change. If the blue screens began after a Windows update, a new driver or new software, remove that change first. Uninstall the update from Settings, Windows Update, Update history, or roll a driver back in Device Manager (right-click the device, Properties, Driver, Roll Back Driver).
- Repair Windows system files. Open Terminal (Admin) and run
sfc /scannow. If it reports damage it could not repair, runDISM /Online /Cleanup-Image /RestoreHealth, restart, and runsfc /scannowonce more. - Return the PC to stock settings. Reset the BIOS to defaults, then leave XMP or EXPO, CPU or GPU overclocks and undervolts (including per-core offsets such as Curve Optimizer) switched off while you test. If the crashes stop, re-enable one setting at a time to find the unstable one.
- Test the memory. Run Windows Memory Diagnostic (search for it in Start) for a quick check, then MemTest86 for several passes if the crashes continue. Any error points to a faulty stick or slot, or to memory settings the hardware cannot run reliably.
When to stop and protect your data
If it only occurs when a specific program or device is in use, uninstall that software or driver and check the maker's support page for a fixed version.
Not sure this is your code?
The stop code appears as text on the blue screen. If the PC restarted before you could read it, open Event Viewer, then Windows Logs, then System, and look for a BugCheck event with ID 1001. You can also search all stop codes.