Office 2021 LTSC End of Life: Upgrade to 2024 Without a Clean Install

Office 2021 LTSC end of life lands on October 13, 2026. After that date, Microsoft stops shipping security updates, bug fixes, and technical support for Office LTSC Professional Plus 2021, Office LTSC Standard 2021, Visio LTSC 2021, and Project LTSC 2021.

The apps keep opening. Word still works. That is exactly what makes this dangerous, because nothing visibly breaks while every newly discovered vulnerability in Word, Excel, Outlook or PowerPoint stays unpatched forever.

If you are an admin with a fleet on 2021, the question is not whether to move. It is how much work the move actually is, and the good news is that it is far less than most people assume.

Short answer: you do not need a clean install, and you do not need to reimage anything. But there is one detail almost every guide gets wrong, and it will make your deployment silently fail. We cover it below.

The deadline: what actually ends on October 13, 2026

Office LTSC 2021 runs on Microsoft's Fixed Lifecycle Policy, which means five years of support with no Extended Support phase afterward. There is no ESU program for Office LTSC 2021 the way there was for Windows 10.

After the cutoff you lose:

• Security updates. No patches for newly discovered vulnerabilities, permanently.
• Bug and stability fixes.
• Microsoft technical support.
• Compliance standing. For anyone under ISO 27001, SOC 2, HIPAA, PCI-DSS or similar, running unsupported software on endpoints is an audit finding.

Your three real options

Option 1: Office LTSC 2024, the like for like move

The direct successor. Perpetual license, offline capable, fixed feature set, no subscription, supported through October 9, 2029.

Best for anyone who chose LTSC 2021 deliberately: air-gapped networks, regulated endpoints, process control machines, shared and kiosk systems, and organizations that simply do not want monthly billing. This is the path this guide covers, because it requires the least change to how you already work.

Option 2: Microsoft 365 Apps, the subscription move

Continuously updated, cloud connected, per user licensing, no end of life date to plan around. Best for connected office workers and organizations already invested in the Microsoft cloud stack.

Worst for the exact scenarios LTSC exists to serve. If you are on LTSC 2021 today, you probably picked it for a reason that has not changed.

Option 3: do nothing

Technically an option. The apps keep running. You are accepting a permanently growing pool of unpatched vulnerabilities on every endpoint, plus the compliance exposure. For most organizations this defers cost rather than avoiding it.

Does the upgrade require a clean install?

No. This is the most common misconception about the 2021 to 2024 move, so let us be precise about what is actually required.

What you do not need:

• A clean Windows install
• Reimaging the machine
• To touch user documents, templates, or settings
• An ISO file of any kind

What you do need:

• To remove Office LTSC 2021 first, because 2021 and 2024 cannot coexist on the same device
• A valid Office 2024 volume (MAK) key
• The Office Deployment Tool

Why 2021 and 2024 cannot sit side by side

This is not Microsoft being awkward. The update channel in Office is a device wide setting, so every Office product on a machine, including Visio and Project, has to share one channel. Office LTSC 2021 requires PerpetualVL2021. Office LTSC 2024 requires PerpetualVL2024, and that is the only channel it supports.

One device, one channel. So the upgrade is necessarily remove then install.

The good part is that the removal and installation happen in a single Office Deployment Tool operation, unattended, in one pass. User settings, preferences, and documents are retained. From the user's perspective, Office closes on 2021 and reopens on 2024.

Step 1: the mistake that breaks most 2021 to 2024 deployments

Search for how to remove old Office before installing 2024 and you will find the same XML snippet everywhere:

<RemoveMSI />

This does nothing to Office LTSC 2021.

RemoveMSI only uninstalls Office versions installed with Windows Installer (MSI), which means Office 2007, 2010, 2013 and 2016. Microsoft's documentation is explicit that RemoveMSI does not uninstall prior versions of Office that use Click-to-Run.

Office LTSC 2021 is Click-to-Run. So is Office 2019. So <RemoveMSI/> will run, report success, remove nothing, and then your Office 2024 install fails or lands in a broken mixed state.

The correct element for removing a Click-to-Run version is <Remove>. Here is the quick reference:

Get this one line right and the rest of the migration is straightforward.

Step 2: the upgrade configuration.xml

This single file removes Office LTSC 2021 and installs Office LTSC Professional Plus 2024 in one pass.

<Configuration>

  <!-- Remove Office LTSC 2021 (Click-to-Run) -->
  <Remove>
    <Product ID="ProPlus2021Volume">
      <Language ID="en-us"/>
    </Product>
  </Remove>

  <!-- Install Office LTSC Professional Plus 2024 -->
  <Add OfficeClientEdition="64" Channel="PerpetualVL2024">
    <Product ID="ProPlus2024Volume" PIDKEY="#####-#####-#####-#####-#####">
      <Language ID="en-us"/>
    </Product>
  </Add>

  <Display Level="Full" AcceptEULA="TRUE"/>

</Configuration>

Adapt it to your environment:

• PIDKEY is your Office 2024 MAK key. If you use KMS on your network, remove the whole attribute.
• Language ID must match your installed 2021 language inside the <Remove> block, or the removal will not find the product. Use fr-fr, es-es, de-de and so on as needed.
• OfficeClientEdition of "64" is recommended. If your 2021 install is 32 bit and you want to stay 32 bit, use "32". You can switch architecture during this upgrade because you are removing first.
• Display Level of "Full" shows progress, which is useful when testing one machine. Switch to "None" for silent fleet deployment.
• Running Standard instead of Professional Plus? Use Standard2021Volume and Standard2024Volume.
• Visio or Project on the device? They must be removed and reinstalled at the 2024 level too, so add their Product IDs to both blocks. They share the device wide channel.

Step 3: run the upgrade

Download the latest Office Deployment Tool from the Microsoft Download Center and extract setup.exe.

Open Command Prompt as Administrator and navigate to your ODT folder:

cd %userprofile%\Desktop\Office

Download the 2024 source files:

setup.exe /download configuration.xml

Then run the upgrade:

setup.exe /configure configuration.xml

The Deployment Tool processes the <Remove> block first, then the <Add> block. Office 2021 comes off, Office 2024 goes on, user data stays put. Watch for "Products configured successfully."

New to the Deployment Tool? Our full walkthrough covers it end to end: how to install Office 2024 LTSC Professional Plus with the Deployment Tool.

Step 4: verify and activate

1. Open Word or Excel
2. Go to File → Account
3. Under Product Information, confirm it reads Office LTSC Professional Plus 2024
4. If you did not include a PIDKEY, click Change Product Key, enter your Office 2024 LTSC Professional Plus key, and click Activate

Deploying across a fleet

The same configuration.xml works at scale. Set Display Level="None" for silent installs and push setup.exe /configure configuration.xml through whatever you already use: Group Policy startup scripts, Microsoft Intune as a Win32 app, Configuration Manager, PDQ Deploy, Action1, or your RMM of choice.

Two practical notes for fleet work:

• Host the source files locally. Add SourcePath="\\Server\Share" to the <Add> element so hundreds of machines are not each pulling roughly 3 GB from the Microsoft CDN.
• Stage it. Pilot group, then one department, then the fleet. The removal step means there is a window where a machine has no Office at all, and you want that window to be predictable.

Frequently asked questions