Microsoft ACPIEx Driver Service Defaults in Windows 11
Default Settings
| Startup type: | Boot |
| Display name: | Microsoft ACPIEx Driver |
| Service name: | acpiex |
| Service type: | kernel |
| Error control: | critical |
| Group: | Boot Bus Extender |
| Path: | %SystemRoot%\System32\Drivers\acpiex.sys |
| Registry key: | HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\acpiex |
Default Behavior
Microsoft ACPIEx Driver is a kernel driver. In Windows 11 it starts by the operating system Boot Loader before the Kernel initialization, as a part of the driver stack. If Microsoft ACPIEx Driver fails to start, Windows 11 tries to record the error details into Event Log and restart the PC, using the Last Known Good configuration. If the Last Known Good configuration can't be used, Windows 11 startup process halts with a Stop error. If you disable or delete the acpiex service, Windows 11 won't start.
Dependencies
If Microsoft ACPIEx Driver doesn't work properly, the following services will not start:
- Microsoft GPIO Class Extension Driver
- Serial UART Support Library
- Serial UART Support Library
- Simple Peripheral Bus Support Library
Restore Default Startup Configuration of Microsoft ACPIEx Driver
1. Run the Command Prompt as an administrator.
2. Copy the commands below, paste them into the command window and press ENTER:
sc config acpiex start= boot
sc start acpiex
3. Close the command window and restart the computer.
The acpiex service is using the acpiex.sys file that is located in the C:\Windows\System32\Drivers directory. If the file is removed or corrupted, read this article to restore its original version from Windows 11 installation media.