Installing Publisher LTSC 2021 with Office 365

Eric Dickes 55 Reputation points
2026-08-08T17:55:09.3833333+00:00

I would like to install Publisher LTSC on the same system as my Office 365 installation. Win11 Pro, also have Project 2003 and Visio 2020. All MSFT programs are 32 bit.

In trying to install Publisher, I get an error that it conflicts with Office 365.

I would like to know if the following option might work:

  1. Uninstall Office 365 and Publisher.
  2. Reinstall Office 365 using the ODT and have it not include Publisher that is part of Office 365.
  3. Install Publisher LTSC. Would that eliminate the conflict and allow both to operate normally? Thanks, Eric
Microsoft 365 and Office | Install, redeem, activate | For business | Windows
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AI answer

2026-08-08T17:55:23.9566667+00:00

No. That plan does not make this a supported side-by-side configuration.

The key compatibility rules are:

  1. Products on the same computer must use the same installation technology when they are the same version.
  2. Products of different versions that both use Click-to-Run and have overlapping Office apps can’t be installed together.
  3. All installed Office-family products must match bitness, which is already true in this case because all are 32-bit.
  4. Products installed on the same computer must use the same update channel.

For the versions mentioned:

  • Microsoft 365 uses Click-to-Run and version 16.0.
  • Office LTSC 2021 also uses Click-to-Run and version 16.0.
  • Office 2016 can be Click-to-Run or MSI, but Office LTSC 2021 is Click-to-Run.

Because Microsoft 365 and Publisher LTSC 2021 are both version 16.0 Click-to-Run products, excluding Publisher from the Microsoft 365 install does not remove the underlying same-version Click-to-Run compatibility requirement. The conflict is not solved simply by reinstalling Microsoft 365 without Publisher.

Also, Microsoft states that in most cases a Microsoft 365 subscription version and a non-subscription version such as Office 2021, 2019, or 2016 can’t run together on the same computer. The MSI exception does not apply to Office LTSC 2021, because LTSC 2021 uses Click-to-Run.

A supported path is to use only one Office generation on that PC, or keep Publisher 2021 on a separate Windows PC or virtual machine if Publisher must be retained while Microsoft 365 remains installed elsewhere.

If proceeding with Office LTSC 2021 deployment generally, the Office Deployment Tool can be used to remove older MSI-based Office products with RemoveMSI, but that applies to MSI installs such as older Office, Visio, or Project versions. For Click-to-Run products such as 2019-family products, the Remove element is required instead.

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  1. Liora 1,630 Reputation points Independent Advisor
    2026-08-09T16:11:56.06+00:00

    Dear @Eric Dickes,

    I hope you’re having a good day. 

    Thank you for providing the details of your environment and the steps you're considering.

    Based on the information you've shared, I would be cautious about proceeding with the uninstall/reinstall plan immediately. The key issue here is determining what is actually causing the conflict before making significant changes to a working Office installation.

    From a technical perspective, there are two possible scenarios:

    Scenario 1: The conflict is specifically related to Publisher

    If the Microsoft 365 installation already includes the Publisher application and the Publisher LTSC 2021 installer is detecting that existing Publisher component, then your proposed approach could potentially work:

    • Uninstall Microsoft 365 Apps.
    • Reinstall Microsoft 365 Apps using ODT and exclude Publisher.
    • Install Publisher LTSC 2021.

    In this scenario, removing Publisher from the Microsoft 365 installation may eliminate the conflict and allow Publisher LTSC 2021 to install successfully.

    Scenario 2: The conflict is between Microsoft 365 Apps and the LTSC product family

    This is the scenario that concerns me more.

    The error message mentions a conflict with Office 365, not necessarily with Publisher itself. In some cases, Office installers block combinations of subscription-based Microsoft 365 Apps and perpetual LTSC products, regardless of whether the individual application is installed. In that case, excluding Publisher from Microsoft 365 would not change the outcome because the LTSC installer would still detect the Microsoft 365 Apps installation and continue to report a conflict.

    If that's what is happening, you could spend considerable time Uninstalling Office - Rebuilding the installation with ODT - Reconfiguring applications only to encounter the same blocking message at the end.

    Since the environment is currently functioning, I don't see enough evidence yet that the Publisher component itself is the root cause of the conflict. The risk of making broad changes is that you could introduce new licensing, activation, or application compatibility issues while trying to solve a problem whose true cause hasn't been identified.

    Before making changes, could you provide:

    • The exact Microsoft 365 product you're running (Apps for business, Apps for enterprise, etc.)?
    • How you're installing Publisher LTSC 2021 (Office Deployment Tool, Volume License media, ISO, etc.)?
    • The complete conflict message or a screenshot of the error?

    Those details may help determine whether the proposed configuration is actually supported before you invest time rebuilding the Office installation.

    Based on the information available so far, I would not recommend uninstalling Microsoft 365 yet. Your proposed plan could work if the conflict is caused by the Publisher application itself, but it may have no effect at all if the conflict is actually between Microsoft 365 Apps and the LTSC installation model. My goal is to help you determine which of those scenarios applies before making major changes to a working system.

    Looking forward to hearing back from you with any updates or additional details.  

    Warm regards,  

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