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Facing the 0xc000012f AppvIsvSubsystems64.dll error while trying to open Microsoft Office apps on Windows 11?
This frustrating error usually means that a critical DLL file is missing or corrupted, preventing Office programs from starting properly.

Don’t worry — in this step-by-step guide, you’ll learn exactly how to fix the issue by replacing the missing file, repairing Office, and restoring full functionality.

Let’s get started.

Why Does the 0xc000012f AppvIsvSubsystems64.dll Error Occur?

The error appears because the AppvIsvSubsystems64.dll file, crucial for running Office applications, is missing or damaged.
Without it, programs like Word, Excel, or PowerPoint cannot launch correctly, and Windows throws up this error message.

The most common causes include:

• Windows or Office updates not completing correctly
• Corrupted Office installation
• Malware or system file corruption

How to Fix 0xc000012f AppvIsvSubsystems64.dll Error Step-by-Step

Follow these methods carefully to solve the problem:

1. Download and Extract the Missing DLL File

• Click the link provided in the video description to download the correct AppvIsvSubsystems64.dll file.
• After downloading, right-click the file, select Show More Options → 7-Zip → Extract Files.
• Click OK to unzip the file.

Tip: Always scan downloaded files with your antivirus for extra safety.

2. Copy the DLL File to the Office Installation Folder

• Open File Explorer.
• Navigate to C:\Program Files\Microsoft Office\root\Office16.
• Paste the AppvIsvSubsystems64.dll file into this folder.
• If prompted for administrator permission, click Continue.

If you cannot paste because an Office app is open:

• Close all Office programs completely.
• If needed, open Task Manager, find Office-related processes, right-click, and select End Task.

3. Paste the DLL File into the Shared Office Folder

In addition to the main Office folder, you need to paste the DLL file here too:

• Go to C:\Program Files\Common Files\Microsoft Shared\ClickToRun.
• Paste the AppvIsvSubsystems64.dll file here as well.
• Grant permission if asked.

4. Restart Your Computer

After pasting the DLL file in both locations:

• Restart your computer.
• Try opening your Office applications again.

If the error persists, move to the next step.

5. Perform an Online Repair of Microsoft Office

If manually copying the DLL does not solve the problem:

• Right-click on the Start Menu → Installed Apps.
• In the search box, type Office.
• Locate Microsoft Office, click the three dots … → Modify.
• Click Yes on the User Account Control prompt.
• Choose Online Repair → Repair.
• Wait for the process to complete.

Online Repair will fix any corrupted or missing Office files automatically.

6. Uninstall and Reinstall Microsoft Office (If Necessary)

If none of the above solutions work:

• Uninstall Microsoft Office completely.
• Restart your computer.
• Reinstall Office using the official installer.

Helpful links to official guides and Office removal tools are usually provided in the video description.

Frequently Asked Questions (FAQs)

What causes the 0xc000012f AppvIsvSubsystems64.dll error in Office?

It usually happens because the essential DLL file needed to run Office apps is missing or damaged.
Common causes include interrupted updates, system file corruption, or malware infections.

Is it safe to replace DLL files manually?

Yes, but only if the file is downloaded from a trusted or official source.
Always scan any files for viruses before copying them into system folders.

Will online repair solve the 0xc000012f error?

In most cases, yes. Online repair checks and replaces all missing or damaged files automatically without affecting your personal data.

What should I do if repairing Office doesn’t fix the error?

If copying the DLL and running Online Repair both fail, the last reliable option is to uninstall and reinstall Microsoft Office entirely.

The 0xc000012f AppvIsvSubsystems64.dll error can be frustrating, but it’s easily fixable with the right steps.
By manually replacing the missing DLL file, repairing your Office installation, or reinstalling the suite if necessary, you can get your Office apps back up and running smoothly.

Follow the guide above carefully, and you’ll resolve the problem in no time!

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