Microsoft Accelerator Class Extension Driver (WinAccelCx0101) Service Defaults in Windows 11

The Microsoft Accelerator Class Extension Driver service exists only in:

Default Settings

Startup type: Manual
Display name:Microsoft Accelerator Class Extension Driver
Service name:WinAccelCx0101
Service type:kernel
Error control:critical
Group:System Bus Extender
Path:%SystemRoot%\system32\drivers\WinAccelCx.sys
Registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinAccelCx0101

Default Behavior

Microsoft Accelerator Class Extension Driver is a kernel driver. In Windows 11 it starts only if the user, an application or another service starts it. If Microsoft Accelerator Class Extension 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 WinAccelCx0101 service, Windows 11 won't start.

Restore Default Startup Configuration of Microsoft Accelerator Class Extension Driver

1. Run the Command Prompt as an administrator.

2. Copy the command below, paste it into the command window and press ENTER:

sc config WinAccelCx0101 start= demand

3. Close the command window and restart the computer.

The WinAccelCx0101 service is using the WinAccelCx.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.