The problem is narrower than some coverage suggests. It affects MSI-based Excel 2016 installations, and Microsoft documents it in workbooks that contain conditional formatting. Microsoft 365 subscribers and Windows 11 users are not affected as a group.
What Microsoft confirmed
Microsoft's KB5002934 support article now says the page originally described build 16.0.5574.1005 and that this release is now updated to build 16.0.5574.1006. Microsoft says the new build includes all security updates for Microsoft Excel 2016, and also fixes the issue that was reintroduced in 16.0.5574.1005, in which paste operations might fail if the workbook contains conditional formatting.
Microsoft did not issue a new KB number for the fix. It replaced the package under the same KB. That matters for administrators, because "KB5002934 installed" no longer tells you whether a machine has the fix. You need to know which revision is installed.
Two details in Neowin's report need correcting:
- The product is Excel 2016. Neowin called it "Excel 2017," which does not exist.
- This is an Office update, not a Windows update. Microsoft distributes it through Microsoft Update, the Microsoft Update Catalog and the Download Center. It is not tied to Windows 11 cumulative or preview updates.
In short: The October Excel 2016 security update brought the paste bug back. Microsoft fixed it by replacing the package under the same KB number.
How the bug came back: a recap
The problem started with the September 8, 2026 security update, KB5002914. Microsoft listed a known issue: some paste operations could fail without any warning. The copied cells stayed selected, nothing changed at the destination, and Excel showed no error message and made no sound.
Microsoft fixed that with KB5002665 on September 16. That fix also had a gap. The KB5002665 page later added a note that an earlier version of the update could still let paste fail in workbooks with conditional formatting, and told customers to install the latest version.
KB5002934 arrived on October 13 and replaced KB5002914. Its first build brought back that conditional-formatting case. In one Microsoft Q&A thread, a user reported that the silent copy/paste failure in Excel 2016 (MSI) has returned immediately after installing the cumulative update KB5002934. A post on Microsoft Tech Community described the same problem on workstations across our organisation.
What users described fits Microsoft's diagnosis, with some details worth noting:
- One user said normal paste failed in existing .xlsm workbooks, and that Paste Special → Values still works. The same user said copy and paste works in a newly created workbook, and that conditional formatting is present in the affected workbooks.
- Another user said removing conditional formatting from an affected worksheet does not resolve the problem. Deleting your formatting rules is therefore not a reliable workaround.
- Several users reported their Excel version as 16.0.5574.1004 after installing the October update. That differs from the .1005 package build Microsoft cites. The version shown in Excel may not match the package build in Microsoft's article exactly, so check update history as well as the version number.
Neowin also suggested that the Windows 11 26H2 rollout distracted Microsoft and caused this. No evidence supports that, and Microsoft has given no reason for the regression, so we are leaving it out.
In short: This is the same silent paste failure from September, specifically the conditional-formatting case that the first KB5002665 package also missed.
Who is affected
| Factor | Affected? |
|---|---|
| Excel 2016, MSI (volume-license) install | Yes, if build .1005 of KB5002934 is installed |
| Office 2016 Click-to-Run (e.g., Office 365 Home) | Download Center package does not apply |
| Workbooks with conditional formatting | The documented trigger |
| New, blank workbooks | Users report these generally work |
| Windows 11 version or Windows updates | Not the cause |
Microsoft says that to install this update you must have the release version of Excel 2016 installed on the computer. The Download Center package covers only the MSI edition of Office 2016, not Click-to-Run.
How to fix it
For MSI-based Excel 2016:
- Confirm your installation type. In Excel, go to File > Account (or Help). Microsoft's KB articles point to its "What version of Office am I using?" guidance. If you have a Click-to-Run install, this package is not for you.
- Check 32-bit or 64-bit. The Download Center has separate x86 and x64 packages.
- Get the revised package. You have three options:
- Microsoft Update. If automatic updates are on, Microsoft says the update downloads and installs automatically. It does not say when the revised build reaches each device.
- Microsoft Update Catalog. Get the standalone package, which is useful for WSUS or manual deployment.
- Microsoft Download Center. Microsoft says you can get the standalone update package through the Microsoft Download Center, and that you should follow the installation instructions on the download page. WindowsDigitals gives the same advice: download the package that matches your Office (32-bit or 64-bit) and run it.
- Confirm it worked. Responses in Microsoft's Q&A forum advise you to verify that Excel is running build 16.0.5574.1006 and test copy/paste again. Test with one of the workbooks that was failing, not a new blank one, because new files usually paste fine anyway.
A temporary workaround
Until the fixed build is installed, Microsoft recommends Paste Special. On the Home tab, open the Paste dropdown and choose Paste Special. KB5002665 lists these options: Formulas, Formulas & Number Formatting, Values, Values & Number Formatting, and Link. In the forum threads, Paste Values with the keyboard shortcut Alt > E > S > V > Enter was the most common choice.
Paste Special does not replace a normal paste. Pasting Values drops formulas, and the other options leave out different things such as formatting or comments. Use it to get through the week, not as a long-term fix.
Should you uninstall the update?
Neowin noted that affected users uninstalled KB5002934 and paste worked again. That is true but risky. KB5002934 is a security update. Microsoft says it resolves Microsoft Excel remote code execution vulnerability and Microsoft Excel Information Disclosure vulnerability, and its article lists 29 CVEs. Removing it to restore paste exposes the machine to malicious spreadsheets, which is how most attacks through Excel start.
Removal can also fail. One user reported that attempts to remove KB5002934 using the Office update removal mechanism (Oarpmany.exe) failed. Microsoft's fix is the revised package, not a rollback.
In short: Install the .1006 package, test on a workbook that was failing, use Paste Special in the meantime, and avoid uninstalling security updates.
Our take
This is partly a story about Office 2016 reaching the end of its life. Microsoft ended support for Office 2016 in October 2025. Updates still arriving for MSI Excel 2016 in late 2026 mainly serve organizations covered by extended arrangements, and those tend to be the shops least able to absorb a broken update. Patches for older software tend to get less real-world testing than current Microsoft 365 builds, and conditional formatting in long-lived business workbooks is exactly the kind of case a smaller test matrix can miss.
Microsoft did document the problem openly on the KB page, which beats leaving admins to piece it together from forum threads. Still, the September fix shipped incomplete, and the October update brought back the case it had missed. That is two misses in five weeks on the most basic action in a spreadsheet.
For administrators, the lesson goes beyond Excel 2016. Office packages can be republished under the same KB number, so check the installed build, not just the KB number. A Tech Community reply recommended testing a minimal workbook with and without conditional formatting on a test machine before rolling out widely.
If your organization still runs MSI Office 2016, this incident is also a good reason to start planning the move to a supported version. Readers running other perpetual Office versions should keep an eye on WindowsForum's Office update and Patch Tuesday coverage. After this autumn, paste is one more thing to test after every update.