Serial UART Support Library (SerCx) Service Defaults in Windows 10

Serial Class Extension by Microsoft Corporation.

Default Settings

Startup type: Manual
Display name:Serial UART Support Library
Service name:SerCx
Service type:kernel
Error control:normal
Registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SerCx

Default Behavior

Serial UART Support Library is a kernel device driver. In Windows 10 it is starting only if the user, an application or another service starts it. If Serial UART Support Library fails to start, the failure details are being recorded into Event Log. Then Windows 10 will start up and notify the user that the SerCx service has failed to start due to the error.


Serial UART Support Library cannot be started under any conditions, if the Microsoft ACPIEx Driver service is disabled.

Restore Default Startup Configuration of Serial UART Support Library

Before you begin doing this, make sure that all the services on which Serial UART Support Library depends are configured by default and function properly. See the list of dependencies above.

1. Run the Command Prompt as an administrator.

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

sc config SerCx start= demand

3. Close the command window and restart the computer.

The SerCx service is using the SerCx.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 10 installation media.