5 Ways to Fix ERROR_ACPI_ERROR 669 (0x29D)

The ERROR_ACPI_ERROR Windows system error, with code 669 (0x29D), appears due to issues in the Advanced Configuration and Power Interface (ACPI). The message reads, An error occurred in the ACPI subsystem.

The system error is caused by misconfigured power settings, problems with the BIOS, corrupted system files, overclocking, and malfunctioning hardware.

Before you proceed to the solutions, reboot the PC, install all pending Windows updates, disable overclocking, and remove any non-critical hardware connected to the PC.

How can I fix ERROR_ACPI_ERROR in Windows?

1. Reset the power plan settings

1. Press Windows + S to open Search, type Control Panel in the text field, and click on the relevant result.
2. Click on System and Security.
3. Click on Change battery settings under Power Options.
4. Now, click on Change plan settings.
5. Click on Restore default settings for this plan.
6. Click Yes in the confirmation prompt.
7. Finally, restart the computer and verify whether ERROR_ACPI_ERROR is fixed.

2. Repair the corrupted system files

1. Press Windows + S to open Search, type Command Prompt, and click on Run as administrator.
2. Click Yes in the UAC prompt.
3. Paste the following DISM commands individually and hit Enter after each: DISM /Online /Cleanup-Image /CheckHealth DISM /Online /Cleanup-Image /ScanHealth DISM /Online /Cleanup-Image /RestoreHealth
4. Now, execute this SFC scan command: sfc /scannow
5. Once done, reboot the PC to apply the changes.

If corrupted system files are causing the ERROR_ACPI_ERROR Windows system error, running the DISM (Deployment Image Servicing and Management) and SFC (System File Checker) scans will replace all problematic files with their cached copies!

3. Uninstall conflicting software

1. Press Windows + R to open Run, type appwiz.cpl in the text field, and hit Enter.
2. Select the conflicting app or any installed around the same time the error first appeared, and click Uninstall.
3. Follow the on-screen instructions to complete the process.
4. Finally, reboot the PC and check for improvements.

In 2 out of 5 cases, a third-party app was responsible for ERROR_ACPI_ERROR. And if its quick removal doesn’t work, use a top-rated software uninstaller to clear any leftover files and Registry entries that might still be conflicting with Windows!

4. Disable ACPI in BIOS

For several users, disabling ACPI in the system’s BIOS fixed the ERROR_ACPI_ERROR An error occurred in the ACPI subsystem message. You will find the option to disable ACPI under the Advanced section.

Since the process is different for each computer model, I recommend you check the manufacturer’s official website for the exact steps.

5. Reset or update the BIOS

When nothing else works, you can always reset the BIOS to fix the Windows system error. To do that, turn off the PC > then power it on > repeatedly press the Esc, Del, F1, F2, F10, or F12 key to access the BIOS > look for the Default, Load Default, or Reset option > select it > confirm the change.

If a reset also fails to resolve ERROR_ACPI_ERROR, update the BIOS. You will find the latest version on the manufacturer’s website. Also, given the critical nature of the process, I recommend you check the exact steps and only then proceed with the update.

By now, you should have fixed ERROR_ACPI_ERROR 669 (0x29D) in Windows. In case the error keeps reappearing, the hardware is to blame. So, it’s best that you visit a local repair shop and get the hardware components inspected for faults.

Before you leave, discover the best performance settings in Windows and prevent such errors from reappearing!

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