Office LTSC 2021 is out of support. How to replace it with Microsoft 365 Apps

Support for Office LTSC 2021, Visio LTSC 2021 and Project LTSC 2021 ended on 13 October 2026, and so did support for the retail Office 2021 suites. Microsoft confirmed it in Message Center post MC1509797 on 15 October. There is no extension and no extended security update programme. The apps keep running, but there will be no more security fixes, bug fixes or technical support.

The last builds those products received came out on the same day. Office LTSC 2021 volume licensed stops at Version 2108 build 14334.20974, and Office 2021 retail stops at Version 2608 build 20326.20232. Every Office CVE published from November onwards will apply to those machines and stay unpatched.

Microsoft offers two ways forward. Microsoft 365 Apps is the default for anything that connects to the internet. Office LTSC 2024, supported until October 2029, is meant for regulated, process control and fully disconnected machines. This guide covers the Microsoft 365 Apps route on Windows.

Before you start

Licences. Users need a plan that includes Microsoft 365 Apps. For enterprises that is Microsoft 365 E3, Office 365 E3 or Microsoft 365 Apps for enterprise. Under 300 users, Business Premium, Business Standard or Apps for business. Visio and Project need their own subscriptions, such as Visio Plan 2 or Project Plan 3 or 5.

Permissions. Local administrator on the target devices, or a deployment tool such as Configuration Manager or Intune that runs as system.

Tools. The Office Deployment Tool (setup.exe) from the Microsoft Download Center, a share or package to hold it, and the Office ADMX templates (Download Center ID 49030) if you manage settings with Group Policy.

Disk and network. At least 4 GB free on the system drive. Delivery Optimization is supported on Windows 10 and 11 and saves a lot of WAN traffic when you upgrade a whole site at once.

Copilot. If these users will get Copilot later, put them on Monthly Enterprise Channel or Current Channel. Copilot needs one of those two channels.

Find what is left

1. If you run Configuration Manager, open the Office 365 Client Management dashboard and build a dynamic collection of devices grouped by Office version. Anything reporting Version 2108 on the PerpetualVL2021 channel is LTSC 2021.
2. On a single machine, open Word and go to File > Account. The product name under Product Information tells you which suite and year is installed.
3. Note which machines also have Visio LTSC 2021 or Project LTSC 2021. They share the same end of support date, so remove them in the same pass and plan their replacement licences at the same time.
4. Split the list. Machines that are genuinely offline or regulated go to Office LTSC 2024. Everything else goes to Microsoft 365 Apps.

Prepare the removal package

LTSC 2021 is a Click to Run product, so the RemoveMSI element does not touch it. That element only handles MSI installs of 2007, 2010, 2013 and 2016. Microsoft's guidance is to uninstall the previous version before installing Microsoft 365 Apps, and for Click to Run products the tool for that is the Remove element.

5. Create remove-ltsc2021.xml next to setup.exe. List each product ID you found in the inventory.

<Configuration>
  <Remove All="FALSE">
    <Product ID="ProPlus2021Volume" />
    <Product ID="VisioPro2021Volume" />
    <Product ID="ProjectPro2021Volume" />
  </Remove>
  <Display Level="None" AcceptEULA="TRUE" />
  <Property Name="FORCEAPPSHUTDOWN" Value="TRUE" />
</Configuration>

Leaving out the Language element removes every installed language for each product. Use Standard2021Volume, VisioStd2021Volume or ProjectStd2021Volume if that is what the device has. FORCEAPPSHUTDOWN closes any Office app that blocks the removal, and users will lose unsaved work, so schedule this outside working hours or leave it out and accept some failures to retry.

Prepare the install package

6. Create install-m365apps.xml in the same folder.

<Configuration>
  <Add OfficeClientEdition="64" Channel="MonthlyEnterprise">
    <Product ID="O365ProPlusRetail">
      <Language ID="en-us" />
    </Product>
  </Add>
  <RemoveMSI />
  <Display Level="None" AcceptEULA="TRUE" />
</Configuration>

Change the language to match your users. Keep RemoveMSI in, because it cleans up any Office 2016 MSI leftovers that sometimes sit on the same machines. If some devices run 32 bit Office today and you want them on 64 bit, add MigrateArch="TRUE" to the Add element. For Remote Desktop session hosts, add <Property Name="SharedComputerLicensing" Value="1" />.

7. Download the source files once to your share so devices do not each pull from the internet.

setup.exe /download install-m365apps.xml

If you plan to install from the share, add SourcePath="\\server\share" to the Add element before you run the download.

Run the upgrade

8. On a pilot device, from an administrator command prompt in the tool folder, run the removal.

setup.exe /configure remove-ltsc2021.xml

The command returns when the removal is complete. Check Apps > Installed apps in Windows Settings and confirm the LTSC 2021 entries are gone.

9. Run the install.

setup.exe /configure install-m365apps.xml

10. Sign in to Word with the user's work account. Microsoft 365 Apps activates against the user's licence. The first launch can show the Your Privacy Matters dialog, and the user must accept it to finish setup.

11. Once the pilot works, wrap both commands into a single deployment. A small batch file that runs the two setup.exe lines in order works as the install command for a Configuration Manager application or an Intune Win32 app.

12. If Configuration Manager was managing Office updates for these devices, disable the Management of Microsoft 365 Apps for enterprise policy for the upgraded collection and confirm the OfficeC2RCom component is no longer registered on the clients. Otherwise Configuration Manager and the new update channel will compete.

Verify it worked

13. Open Word and go to File > Account. You should see Microsoft 365 Apps for enterprise under Product Information, the signed in user, and Monthly Enterprise Channel next to the version.
14. Compare the build with the current Monthly Enterprise build. In October 2026 the security update builds are 20430.20180 for Version 2609, 20326.20232 for 2608 and 20228.20276 for 2607.
15. Next to Update Options confirm Updates are automatically downloaded and installed is shown.
16. Rerun your inventory query from step 1. The device should drop off the LTSC 2021 list.

Clean up the stubborn ones

17. If the removal fails or leaves broken entries, use the scrub scenario in the Microsoft Support and Recovery Assistant command line tool.

SaRAcmd.exe -S OfficeScrubScenario -AcceptEula -OfficeVersion All

Replace All with a specific version if you only want to remove one release. Restart the device and run the install package again.

Troubleshooting

Symptom	Likely cause	What to do
Visio or Project 2021 still installed after the upgrade	Product IDs missing from the removal file	Add their product IDs to the removal file and run it again
Removal reports success but LTSC still listed	An Office app was open and blocked removal	Add FORCEAPPSHUTDOWN or schedule the job when users are signed out
Office installs but will not activate	User has no Microsoft 365 Apps licence	Assign the licence and have the user sign in again
Office cannot activate after install	Wrong product ID in the install file	Check the Product ID value, the wrong ID prevents activation
Device lands on Current Channel	Channel attribute missing	Set Channel="MonthlyEnterprise" in the Add element or set Update Channel by policy
Updates fight with Configuration Manager	Office 365 client management still on	Disable the Management of Microsoft 365 Apps for enterprise client setting
Bandwidth spikes on a site	Every device downloading from the CDN	Install from a local share and turn on Delivery Optimization
Users still prompted for privacy settings	First run dialog	Expected, the user accepts once

The machines that hold this up are rarely the desktops. It is the one PC on a lab bench or a production line that runs a macro nobody has tested on a newer build, and someone will ask for an exception. Give those a date for moving to Office LTSC 2024 instead of leaving them on an unsupported product, because LTSC 2024 keeps them fixed in place and still patched until 2029.