System Error 126 when you start the Windows Modules Installer service (TrustedInstaller): The specific module could not be found
This article helps fix the System Error 126 that occurs when you start the Windows Modules Installer service.
Applies to: Windows 7 Service Pack 1, Windows Server 2008 R2 Service Pack 1
Original KB number: 959077
Symptoms
When you start the Windows Modules Installer service, you receive the following error message:
You also receive an error message at the command prompt:
Cause
This issue occurs if the following registry subkey is changed:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\Version
Resolution
To resolve this issue, you have to re-create the expandable string value of the registry subkey that is mentioned in the Cause section.
First, you have to check whether the registry subkey exists. To do this, start Registry Editor, and then browse to the subkey that is mentioned in the Cause section. If the subkey does not exist, you must create it. To do this, follow these steps:
Locate the
C:\Windows\Servicing\Version
directory, and note the name of the subfolder in this directory. It will be named something like 6.1.7600.16385. This is your TrustedInstaller ID.Copy the subfolder name to the clipboard, and then paste it into Notepad for safekeeping.
Note
In this example, the TrustedInstaller ID is 6.1.7601.17592.
In the
C:\Windows\WinSxS
directory, find a subfolder whose name begins with one of the following strings. (In the following subfolder names, the placeholder TrustedInstaller ID represents your TrustedInstaller ID.)For 32-bit Windows: x86_microsoft-windows-servicingstack_31bf3856ad364e35_ TrustedInstaller ID _none
For 64-bit Windows: amd64_microsoft-windows-servicingstack_31bf3856ad364e35_ TrustedInstaller ID _none
Copy the subfolder name to the clipboard, and then paste it into Notepad for safekeeping.
Create the registry subkey
HKLM\Software\Microsoft\Windows\CurrentVersion\Component Based Servicing\Version
.Note
To create this key, you have to be an owner of the Component Based Servicing key. Then, you have to then give yourself full access permissions.
On the Version key that you created in step 5, create an expandable string value (or edit it if it already exists). To do this, use the TrustedInstaller ID as your name, and use the full path of the folder that you identified in step 3 as the value.
Note
In the full path, you must use
%SystemRoot%\WinSxS\folder_name
instead ofC:\Windows\WinSxS\folder_name
.Click OK, and then exit Registry Editor.
You can now start the Windows Modules Installer (TrustedInstaller) service as usual.
Data collection
If you need assistance from Microsoft support, we recommend you collect the information by following the steps mentioned in Gather information by using TSS for deployment-related issues.