Critical Software ✓ Solution Verified by Community (30+ upvotes)

Error Code kmode-exception-not-handled — Mozilla Firefox

Kernel-mode program generated an exception the error handler didn't catch. Usually a driver issue.

✅ 60% úspěšnost
👥 30+ uživatelů ověřilo
📅 Aktualizováno: 2026-08-12
⏱️ 20 min čtení
Oprava založena na komunitních zprávách a expertní analýze. Naposledy ověřeno: 2026-08-12 · Jak ověřujeme opravy
Error Codekmode-exception-not-handled
Affected SystemMozilla Firefox (Mozilla)
DifficultyCritical
Estimated Time20 min
Requires Admin Rights⚠️ Yes
Requires Reboot🔄 Yes

Postup řešení

  1. 1 Restart Mozilla Firefox completely. Close it, open Task Manager (Ctrl+Shift+Esc), find any remaining Mozilla Firefox processes, right-click → End Task. Background processes from previous sessions are the most common cause of startup crashes.
  2. 2 Update Mozilla Firefox to the latest version. Open the app, go to Help → Check for Updates (or download the latest installer from the official website). Updates fix known bugs and compatibility issues.
  3. 3 Reset Mozilla Firefox settings. Navigate to %APPDATA%\MozillaFirefox and rename the settings folder to add '.old'. This forces Mozilla Firefox to create fresh settings — corrupted config files cause crashes.
  4. 4 Run Mozilla Firefox as Administrator. Right-click the shortcut → Properties → Compatibility → check 'Run as Administrator'. Some features of Mozilla Firefox require elevated permissions.
  5. 5 Check if Mozilla Firefox conflicts with your antivirus. Temporarily disable real-time protection and test. Add Mozilla Firefox installation folder to antivirus exclusions.
  6. 6 Clear Mozilla Firefox cache. Navigate to %LOCALAPPDATA%\MozillaFirefox\Cache and delete all files. Corrupted cache data causes rendering and processing errors.
  7. 7 Repair Mozilla Firefox installation. Windows Settings → Apps → Mozilla Firefox → Modify → Repair. This replaces damaged program files while preserving your data.
  8. 8 If Mozilla Firefox still won't work: uninstall from Settings → Apps, restart, reinstall from official website. A clean install is the nuclear option but fixes almost everything.

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