Windows reports an AcLayers.dll error

[German]Some Windows users run into the problem that when they start programs, an error message appears stating that AcLayers.dll is not intended to run on Windows or contains an error. Here is a brief look at this issue.

Windows reports an AcLayers.dll error

I accidentally became aware of this problem the other days through a post on Facebook. A user gets an error message when calling various programs:

Regsvr32.exe –  Invalid image

C:\WINDOWS\SYSTEM32\AcLayers.dll  is either not designed to run on Windows or contains an error. Reinstall the program using the original installation media, or contact the system administrator or software vendor for assistance. Error status 0xc000012f

The above screenshot contains the error message in question, although the path makes me wonder a bit, since the file should be found in various places like WinSxS or under c:\Windows\AppPatch\Aclayers.dll. Since in the FB group in question immediately came a link to one of the obscure websites that help with such a problem through 'tools', I post a few lines on the subject. 

The error code 0xC000012f

The error code 0xC000012f stands for STATUS_INVALID_IMAGE_NOT_MZ and says "The specified file did not have the correct format. MZ was missing from the beginning of the file.". Ergo, the DLL file is simply corrupted and therefore cannot be loaded.

More cases found

If you search the internet for the filename, you will get a lot of hits from sites, which want to give you a repair tool for the broken file in a more or less difficult way. Here I can only say 'Hands off'. In the Microsoft Answers forum there are several hits here, here and here. The following forum description is typical:

msi.dll and AcLayers.dll is either not designed to run on Windows or it contains an error.

Hi, this just started happening.

AcLayers.dll and msi.dll is either not designed to run on windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc000012f

Happened for no reason, I just updated to the latest version. I tried running the thing that checks system files for errors (forgot what it was called but it was through cmd.exe) and restarting my PC.

The user is 'suddenly' confronted with the error and cannot make sense of it. According to the above hints, the .dll data is now simply broken or the version does not match the Windows version. For the repair I give some hints below. .

AcLayers.dll: Compatibility library

The file Aclayers.dll has been used for many Windows versions. I got a hit in a quick search in WinSxS in my Windows 7. In the properties of the file I find the following: 

So it is a compatibility library that is installed by some programs and then used.

Hands off from downloads or repair sites

I already mentioned it above, when searching the web for the file name, there are a number of hits that provide explanations for repair. Often, links for 'repair tools' are mixed in with the text – because the goal of these pages is to get these useless or harmful tools onto the user's system. Therefore hand off. Also the don't download the DLL from a non Microsoft website should – there are incalculable risks.

How to repair the error?

The approach to repair is to run a system file check using sfc.exe at a command prompt. To do this, open an administrative command prompt (via Run as administrator) and use the command:

sfc /scannow

This command checks the system files for validity and repairs damaged data if necessary. If you are lucky, all files can be repaired. If Windows reports damaged files that could not be repaired, you can try another run with the above command just to be safe. On Windows 8.1 or Windows 10, you can also try the dism command to repair the damaged files:

DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:\RepairSource\Windows /LimitAccess

where the placeholder C:\RepairSource\Windows points to the source where the file exists (see also this Microsoft support article). This can be a Windows installation image, though I'm not sure that AcLayers.dll can be repaired this way – you have to test. 

Occasionally, AcLayers.dll is updated by Windows cumulative updates. In the latest cumulative updates for Windows 10, I found an updated file in the changed update packages. It is possible that installing the latest Windows update will help. However, manually replacing the broken file with a variant from a cumulative update is only something for specialists who know what they are doing, and is not addressed here.

If the repair does not work using the approaches outlined above, Windows should be reinstalled. This step and the subsequent updates should result in a functional version of AcLayers.dll.