October 2026 Office Changes: Publisher Dies, Office 2021 Support Ends
Publisher 365 stops working on October 1, 2026, and that is just the first of eight October 2026 Office changes. Within days, Exchange Web Services starts shutting down in Exchange Online, Word’s Similarity Checker is deleted on October 3 and Teams live chat closes on October 5. Then on October 13, Office 2021 loses all support and the Microsoft 365 feature freeze on Windows 10 spreads to more businesses. If you use Publisher, still run Office 2021 or manage a Microsoft 365 tenant, you have days, not weeks, to act. Here is every change in date order, what it means for you and what to do about it.
To paraphrase T.S. Eliot, “October is the cruelest month”, at least for Microsoft’s paying customers.
Most of these changes land on Patch Tuesday, October 13, but the two most likely to hurt you arrive twelve days earlier, and one of them is a genuine kill switch that switches Publisher off.
October 1: Publisher stops working for Microsoft 365 subscribers
This is the only item on the list that is a kill switch, not just an end of security patches.
Microsoft’s support page says Microsoft 365 subscribers will not be able to access Publisher after October 1, 2026. Translation: Publisher 365 will stop working completely.
You will not be able to open or edit Publisher files in Publisher 365, and the app disappears from the install and download options. The app does not limp on, unsupported. It goes away.
See Microsoft Publisher Ends October 2026: How to Keep It Working.
Publisher’s .pub format is proprietary and nothing else reads it reliably. Save your .pub files as PDF before October 1, and keep the original .pub files too. Converting to Word is Microsoft’s risible recommendation that gives poor results.
Watch out: plenty of coverage quotes October 13 for Publisher. That date applies only to Publisher 2021, the perpetual license version (see the Office 2021 section below). If you are on a Microsoft 365 subscription, October 1 is the end date.
October 1: Exchange Web Services blocked in Exchange Online
Not an app, but it will break things. Any tenant with EWSEnabled still set to Null on October 1, 2026 will have that value flipped to False as the rollout proceeds, which blocks Exchange Web Services for every application in the tenant. The full permanent shutdown follows on April 1, 2027, with no exceptions.
This is Exchange Online only. EWS in on premises Exchange Server is untouched. The most likely breakages are in older third party software: backup tools, archiving products, CRM plugins, email signature managers and migration tools.
Some Microsoft features, including parts of classic Outlook and Power Query in Excel, have used EWS too, so check the usage report before assuming only third party tools are affected.
What to do: check EWSEnabled in your tenant now and pull the EWS usage report. Of everything in this article, this is the change most likely to generate support tickets nobody saw coming.
October 3: Word Similarity Check is deleted
Microsoft is deleting Word’s Similarity Checker, the plagiarism check built into the Editor pane, on October 3, 2026.
October 5: Teams live chat closes
Microsoft is shutting down the Teams live chat widget on October 5, 2026, roughly 18 months after launching it. New setups have been blocked since August 6, 2026.
After the cutoff the widget stops relaying customer messages from your website into Teams. Historical chat content already stored in the Teams channel stays put and is not deleted. Any widget still sitting on a website after October 5 simply becomes hidden.
What to do: find the tag with id=”chatbot” on your web pages and remove it before October 5. Microsoft is pointing customers toward Dynamics 365 Contact Center or Copilot Studio as replacements, both of which are considerably more product than a small business asked for.
Sometime in October: Teams calendar sync with Google Workspace ends
Microsoft has not committed to a day for this one, which is itself worth knowing. Microsoft’s Message Center post MC1462469 lists the retirement as simply “October 2026” and puts an “Act by” date of October 1, 2026 on the admin tasks.
When it happens, calendars that were previously matched and configured will stop syncing, and administrators lose access to the calendar sync setup inside the Admin app in Teams. The Admin app itself is being retired in the same month, so the settings screen may well vanish before the sync does.
What to do by October 1: open the Admin app in Teams and retrieve your account matching information while you still can. For people who need to schedule Teams meetings from Google Calendar afterward, the supported path is the Microsoft Teams Meeting add on for Google Workspace, which is one way scheduling rather than two way sync. That is a downgrade, not a replacement, and it is worth telling your users so plainly.
October 13: the entire Office 2021 family
Support ends October 13, 2026 for all Office 2021 products, including the LTSC variants.
Retail products retiring
For both Windows and Mac desktop apps.
- Office 2021 (the suite)
- Word 2021, Excel 2021, PowerPoint 2021, Outlook 2021, OneNote 2021, Access 2021
- Publisher 2021
- Project 2021
- Visio 2021
Volume license (LTSC) products, same day
- Office LTSC 2021 and Office LTSC 2021 for Mac
- Word LTSC 2021, Excel LTSC 2021, PowerPoint LTSC 2021, Outlook LTSC 2021, OneNote LTSC 2021, Access LTSC 2021
- Publisher LTSC 2021
- Project LTSC 2021
- Visio LTSC 2021
- Skype for Business LTSC 2021
The apps keep working. What stops is technical support, bug fixes and security fixes. Microsoft Update stops delivering Office 2021 updates, and phone and chat support ends. Any security flaw found after that date is likely to stay unpatched.
However, Office 2019 Is Still Getting Security Updates, But Only for Some, so it’s possible a similar thing will happen for some Office 2021 customers. We’ll have to wait for later Patch Tuesday updates to see what Microsoft does.
See our guide to Office 2021 alternatives, including ones that Microsoft doesn’t mention.
October 13: the Microsoft 365 feature freeze on Windows 10 spreads
If you run Microsoft 365 Apps on Windows 10, your new features have already stopped or are about to, depending on your update channel. Version 2608 reached Current Channel in August 2026 and reaches Monthly Enterprise Channel on October 13, 2026.
Microsoft 365 apps on Windows 10 will sit on Version 2608 and get security updates only, until October 10, 2028 or about 2 years from today. See Windows 10 Users: Microsoft 365 Just Stopped Getting New Features.
This is not an app dying. It is Word, Excel, Outlook and the rest becoming a fixed feature set on Windows 10. New features and ribbon changes go to Microsoft 365 on Windows 11 only.
October 13: Microsoft 365 Apps on Windows Server 2022
It’s a similar story for Microsoft 365 apps on Windows Server 2022. Microsoft will keep issuing security updates for the desktop apps on Server 2022 until October 10, 2028 or about 2 years from today, and those machines freeze at Version 2608 as well.
This bites anyone running Office on Remote Desktop Session Hosts or Citrix on Server 2022, which is a lot of small and medium businesses that do not think of themselves as running a server product.
Also on October 13, not Office but same day
- Windows 11 version 24H2 reaches end of servicing for Home and Pro. Enterprise and Education stay supported until October 12, 2027 or about 1 year from today.
- Windows Server 2022 moves from mainstream to extended support.
What software is affected in October 2026
Publisher on a Microsoft 365 subscription
This is urgent because Publisher 365 will stop working completely, not just end support. Check out our guide to your options for keeping Publisher alive or at least maintaining access to your .pub files.
Office 2021
Nothing breaks on October 14. Your files still open, your software still runs. But there is no paid safety net this time, so treat it as a security decision rather than a deadlne.
Microsoft’s recommended paths are Microsoft 365 or Office 2024, but there are other choices.
Windows 10 with Microsoft 365
Your Microsoft 365 apps are safe and supported until October 2028 or about 2 years from today but no new or changed features after version 2608.
You can keep using Windows 10, especially with the ESU option, but don’t get excited when you read about something new in the Microsoft 365 apps because that’s limited to Windows 11.
If you are the admin
Three things, in this order. Check EWSEnabled in Exchange Online and pull the EWS usage report. Save your Google Workspace account matching data out of the Teams Admin app. Strip the chatbot widget tag off your website. All three are October 1 to October 5 work, and none of them will remind you.
More on October 2026 Office Deadlines
If Publisher is part of your working week then Microsoft Publisher Ends October 2026: How to Keep It Working explains the difference between the October 1 kill switch and the October 13 end of support, and How to Install Only Publisher and Skip the Rest of Microsoft Office shows how to set up an older copy without it clashing with Microsoft 365.
Anyone still running Office 2021 should read Office 2021 Support Ends October 13: Your 5 Options Before the Deadline which compares Microsoft 365, Office 2024, waiting for the next Office and the free web apps, with real prices, before the support clock runs out.
For Windows 10 users the frustrating detail is in Windows 10 Support Extended to 2027, But Not for Your Office Apps which explains why an extra year of Windows ESU does nothing for the version 2608 feature freeze. If you are moving off Windows 11 24H2 before October 13 then Windows 11 26H2: 5 Improvements for Microsoft Office Users shows the five settings worth changing first.
October doesn’t stop at the big items. Word users lose a feature on October 3, covered in Microsoft Kills Word’s Similarity Checker on October 3, 2026 along with the plagiarism checkers worth switching to, and Microsoft 365 Companion Apps Die December 16: Uninstall Them Now is the next deadline after that. Keep Microsoft Office Support End Dates 2026: The Complete Checklist bookmarked for every date that follows.