Fix Error 0xC0140015: ACPI Mutex Level Mismatch

Quick Fix: Restart and Check for Updates (30 seconds)

This error usually pops up when Windows tries to load a driver or system file that expects a certain ACPI mutex level, but the firmware or another driver set it wrong. It often happens after a Windows update, a driver install, or a power failure that messed with the system's ACPI tables.

Restart your computer normally. Don't hold the power button — use Start > Power > Restart. A full restart clears temporary ACPI state that can cause mutex mismatches.
Run Windows Update manually. Go to Settings > Update & Security > Windows Update, click "Check for updates". Install any pending updates, then restart again.
Check for driver updates. Go to Settings > Windows Update > Advanced options > Optional updates. Look for driver updates, especially for chipset or ACPI-compliant system devices. Install them.

Expected outcome: After reboot, the error should be gone. If you still get the blue screen or the error code appears in Event Viewer, move to the moderate fix.

Moderate Fix: Disable Fast Startup and Run SFC (5 minutes)

Fast Startup can cause ACPI state to be cached improperly between boots, which triggers this mutex error. This fix tackles that and fixes corrupted system files.

Turn off Fast Startup. Go to Control Panel > Power Options > Choose what the power buttons do. Click "Change settings that are currently unavailable". Uncheck "Turn on fast startup (recommended)". Click Save changes.
Run System File Checker (SFC). Open Command Prompt as Administrator (right-click Start > Windows Terminal (Admin)). Type sfc /scannow and press Enter. Wait for it to finish — this checks system files for corruption. It takes 5-10 minutes. If it finds issues, it'll repair them automatically.
Run DISM before SFC if SFC fails. If SFC says it can't fix everything, run DISM /Online /Cleanup-Image /RestoreHealth first, then run sfc /scannow again. DISM fixes the system image that SFC depends on.

Expected outcome: After disabling Fast Startup and repairing system files, reboot. The ACPI mutex error should not appear. If it does, the advanced fix is needed.

Advanced Fix: Update BIOS and Check ACPI Driver Versions (15+ minutes)

This error ultimately comes from a mismatch between the ACPI tables in the BIOS and what Windows drivers expect. The real fix is to get the firmware and drivers aligned.

Update your BIOS/UEFI firmware. This is the most reliable fix. Visit your motherboard or laptop manufacturer's support page. Look for your exact model. Find the latest BIOS update. Read the release notes — if it says "Update ACPI tables" or "Improve system stability", that's your fix. Follow the instructions exactly: usually it means downloading a file, extracting it to a USB drive, then booting into the BIOS menu (press F2, Del, or F10 at startup) and using the built-in update tool. Warning: A failed BIOS update can brick your machine. Only do this if you're comfortable, and don't interrupt the process.
Check chipset driver version. Go to Device Manager (right-click Start > Device Manager). Expand "System devices". Look for "ACPI-compliant system", "Intel(R) Chipset", or similar. Right-click each, select Properties > Driver tab, note the version. Compare to the latest from your motherboard manufacturer's driver page. If yours is older, download and install the latest chipset driver.
Update PCI Express and power management drivers. In Device Manager, under "Batteries" and "System devices", update drivers for "Microsoft ACPI-Compliant Control Method Battery" and "ACPI-Compliant Embedded Controller". Use the same right-click > Update driver > Search automatically method.
Check for third-party ACPI filter drivers. Some antivirus, VPN, or virtualization software installs ACPI filter drivers that cause mutex conflicts. Uninstall any software you recently added before the error started. Use Revo Uninstaller for a thorough cleanup, or manually remove via Programs and Features.

Expected outcome: After a BIOS update and driver refresh, the ACPI mutex level error should be permanently fixed. Reboot and verify the error doesn't return in Event Viewer under Windows Logs > System, filtering by source "ACPI" or checking for bugcheck codes.

Still stuck? Reset Windows

If none of the above works, you likely have deep corruption in the ACPI subsystem. A Windows reset without deleting your personal files (Settings > Update & Security > Recovery > Reset this PC > Keep my files) can fix this, but you'll need to reinstall drivers and apps afterward. I've seen this error vanish after a clean install of Windows 10 or 11.

One more thing: This error can also crop up on some older laptops (2015-2018) that have BIOS-level power management bugs. If you're on a Dell or Lenovo from that era, check their support forums for a known BIOS update that specifically addresses ACPI mutex issues.