How to fix Error 0xc000012f.

Tamara Thomas 0 Reputation points
2026-10-16T23:33:11.2666667+00:00

The system will not allow any Microsoft office products to be opened. When attempting to run a modify from the installed apps section, the computer will not respond and continues to give "C:\Program Files\Common Files\MicrosoftShared\ClickToRun\C2RUI.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."

Microsoft 365 and Office | Install, redeem, activate | For home | Windows
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  1. AI answer

    2026-10-16T23:33:52.03+00:00

    Because Modify invokes the same damaged Click-to-Run component, repair Windows first, then remove Office with Microsoft’s uninstall troubleshooter and reinstall it rather than retrying Modify.

    1. Repair the Windows component store and system files

    1. Select Start, type Command Prompt.
    2. Right-click Command Prompt and select Run as administrator.
    3. Run these commands in this order:
    DISM.exe /Online /Cleanup-Image /RestoreHealth
sfc /scannow

    Wait for DISM to report that the operation completed successfully and for SFC to reach 100%. Microsoft specifies running DISM before SFC because DISM supplies the components SFC uses for repair.^1^

    1. Restart Windows.
    2. Test Word or Excel once.

    A closely matching case—Office applications and the uninstaller both failing with 0xc000012f and naming C2RUI.dll—uses this repair-first, complete-removal, and reinstall sequence.^2^

    2. If the error remains, remove Office without using Modify

    Your path names the Click-to-Run component, so use Microsoft’s uninstall troubleshooter:

    1. Open Microsoft’s Uninstall Microsoft 365 or Office from a PC page.
    2. Under Click-to-Run, start the uninstall troubleshooter.
    3. If prompted that the site wants to open Get Help, select Open.
    4. Complete the prompts and restart when requested.

    Run it on the affected PC. It requires Windows 10 or later and supports Microsoft 365, Office 2021, Office 2019, and Office 2016, but currently not Office 2024.^3^

    Removing Office does not delete documents, workbooks, or other files created with Office.^3^

    3. Reinstall and activate Microsoft 365

    1. Go to the Microsoft 365 Apps page identified in Microsoft’s installation instructions.
    2. Sign in with the Microsoft account associated with the subscription or purchase.
    3. Select Install apps, then Install or Microsoft 365 apps.
    4. Run the downloaded setup and approve the User Account Control prompt.
    5. Open Word when installation finishes and accept the license agreement or complete the Activation Wizard.^4^

    If the uninstall troubleshooter also fails

    Microsoft documents a manual Click-to-Run removal procedure, but it is lengthy, requires administrator access, deletes Office files/services/tasks and registry keys, and can create serious problems if performed incorrectly. Use it only after the troubleshooter fails, and back up the registry before changing it.^5^

    Do not download an individual C2RUI.dll from a DLL-download site or copy one from another PC. Repair or reinstall the complete Office package instead.

    References

    1. Use the System File Checker tool to repair missing or corrupted system files | Microsoft Support
    2. Word and Click-to-Run both fail with Bad Image error 0xc000012f - Microsoft Q&A
    3. [Click-to-Run](https://support.microsoft.com/office/lifecycle/officeinstall/uninstall-microsoft-365-or-office-from-a-pc)
    4. Download, install, or reinstall Microsoft 365 or Office 2024 on a PC or Mac
    5. Manually uninstall Office
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    1 person found this answer helpful.
  2. Hendrix-V 20,225 Reputation points Microsoft External Staff Moderator
    2026-10-17T07:53:49.3933333+00:00

    Hi Tamara Thomas,

    Since the error specifically references C2RUI.dll under the Office Click-to-Run folder, and the usual repair options have already been covered, the next step is to determine whether the problem is limited to your current Windows profile.

    Please try:

    1. Create a new local Windows user account.
    2. Sign in to the new account.
    3. Try opening Word or another Office application.

    If Office works there, this points to something within the original Windows user profile rather than the Office installation itself. If the same 0xc000012f error occurs, please let us know the exact error shown in the new account as well.

    I hope this helps narrow down the cause, and please feel free to share the result.

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  3. Ivan B 125.3K Reputation points Independent Advisor
    2026-10-17T00:17:57.6833333+00:00

    Hii,

    If the Q&A Assist procedure did not work, I recommend uninstalling the entire Office suite. If that is not possible, follow the procedure described below:

    Perform the manual uninstallation procedure for Click-to-Run and MSI:

    https://support.microsoft.com/en-us/office/lifecycle/manually-uninstall-office

    After uninstalling, restart your PC and reinstall your Office suite.

    Please consider rating the question (accepting the answer or not) and visiting the Microsoft Q&A community if you have further questions.

    Thanks.

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