Microsoft has confirmed that September 2026 Office updates can make copy and paste fail silently in Excel 2024, 2021, 2019 and 2016. The copied cells can remain selected while the destination stays unchanged, with no warning to tell the user that nothing was pasted. Microsoft has now fixed some versions, but others still have limitations.
What businesses need to know
- Microsoft last updated its public guidance on 18 September 2026.
- Office LTSC 2024 and Office LTSC 2021 have fixes in their latest builds.
- Office LTSC 2019 and Office 2016 are only mitigated; paste can still fail in workbooks containing conditional formatting.
- Paste Special is Microsoft’s published workaround when normal paste fails.
- This is an Office update issue, so do not assume every Windows PC or every Microsoft 365 subscription user is affected.
What changed in Excel?
After September’s Office security updates, some versions of Excel began accepting a copy command but failing to complete the paste. Microsoft describes a silent failure: the original range remains selected and the target cells do not change.
That behaviour matters because it looks less like a crash and more like a missed click. A user may repeat the action, switch documents or begin typing information manually without realising that the problem was introduced by an update.
On 18 September, Microsoft updated its known-issue page for Excel paste failures with build-specific fixes and mitigations. The advice now differs by Office version, so the first step is to identify exactly what is installed.
Which Excel versions are affected?
Microsoft lists Excel 2024, Excel 2021, Excel 2019 and Excel 2016, together with Excel Online in Office Online Server. These are perpetual or server-based Office products rather than the standard Microsoft 365 Apps subscription releases.
| Version | Microsoft’s current status |
|---|---|
| Office LTSC 2024 | Fixed in build 17932.21000 |
| Office LTSC 2021 | Fixed in build 14334.20918 |
| Office LTSC 2019 | Mitigated in build 10417.20208; conditional-formatting workbooks may still fail |
| Office 2016 | Mitigated by KB5002665; conditional-formatting workbooks may still fail |
If the user has Microsoft 365 Apps, do not apply a perpetual-Office update simply because the symptoms look similar. Check the product name, update channel and build under File > Account > About Excel, then investigate the installed version properly.
What will users notice?
The problem can affect ordinary copy-and-paste work without producing an error message. Typical signs include:
- the copied cells keep their moving selection border;
- the intended destination cells remain unchanged;
- pressing Ctrl+V or choosing Paste appears to do nothing;
- the same workbook may behave differently when conditional formatting is present;
- Paste Special may work when ordinary paste does not.
A practical example is an accounts user copying invoice lines into a monthly workbook. If the paste fails silently, the totals may remain incomplete. Retyping the rows by hand creates a second risk: duplicated, omitted or mistyped figures.
What should affected businesses do?
- Confirm the Office product and build. Open Excel and go to File > Account > About Excel. Record the full version and whether it is LTSC, MSI-based Office 2016 or Microsoft 365 Apps.
- Install the correct current update. Office LTSC 2024 and 2021 users need the fixed builds listed by Microsoft. Office 2019 and 2016 users should install the mitigation appropriate to their version.
- Test a harmless workbook. Copy a small range into blank cells, then repeat the test in a workbook that uses conditional formatting. Do not test by overwriting live business data.
- Use Paste Special where necessary. Microsoft recommends options including Formulas, Formulas and number formats, Values, Values and number formats, or Paste Link.
- Tell users what failure looks like. The absence of an error does not mean the paste succeeded. Ask staff to check the destination before closing or sending important workbooks.
- Escalate persistent failures. Record the Office build, workbook type and whether conditional formatting is used so support can distinguish this known issue from add-ins, clipboard software or file corruption.
Businesses should not remove September’s security update as a routine fix. It contains security corrections, and rolling it back can replace a productivity problem with a security exposure. Any rollback should be assessed and managed by the IT provider responsible for the device.
Microsoft Office support
Still unable to paste in Excel?
KES can identify the exact Office release, apply the correct supported update and check whether the workbook is affected by the remaining conditional-formatting limitation.
- Office version and build checks
- Managed Microsoft and Windows updates
- Workbook and add-in troubleshooting
- Practical support for affected users
Using Office 2021?
Office 2021 reaches end of support on 13 October 2026, so this may also be the right time to review the replacement plan.
Read the Office 2021 support guide →What happens if the business does nothing?
The issue does not normally destroy the source data. The risk is that work is incomplete without the user noticing. Calculations, reconciliations, reporting packs and imported lists can all be wrong if an expected paste never reaches the destination.
Manual retyping is slower and more error-prone. In a shared workbook, one person may also assume that another has already transferred the information. Until the affected build is updated and tested, staff should verify important pasted ranges before relying on them.
Why does this matter to a UK SME?
Many smaller firms continue to use perpetual Office releases on accounts PCs, reception desks and line-of-business workstations. Those devices may not receive the same update attention as Microsoft 365 subscription installations, even though they handle important operational data.
The mixture of fixed and only partly mitigated versions also makes blanket advice unsafe. A business may have Office 2021 on one PC and Office 2016 on another, with different outcomes after updating. Accurate inventory and managed patching are more useful than asking every user to try random repairs.
KES’s earlier coverage explains why the September Microsoft security updates still matter, while the recent File History warning shows why post-update checks should include both productivity and backup functions.
Has Microsoft completely fixed the Excel paste problem?
No. Microsoft says the latest Office LTSC 2024 and 2021 builds contain fixes. Office LTSC 2019 and Office 2016 have mitigations, but paste operations may still fail in workbooks that contain conditional formatting.
Does this affect Microsoft 365 Apps?
Microsoft’s published affected-products list names Excel 2024, 2021, 2019 and 2016, plus Excel Online in Office Online Server. It does not list the standard Microsoft 365 Apps subscription release. Check the installed product and build instead of assuming the cause from the symptoms alone.
Can users work around it?
Microsoft recommends trying Paste Special and choosing an appropriate option such as Values or Formulas. This is a workaround, not proof that the underlying Office installation is fully fixed.
The practical next step
Check the Office version and build on any PC reporting the problem, install the applicable supported update, and test normal paste and Paste Special in a copy of the affected workbook. Where conditional formatting is involved, keep users informed that the Office 2019 and 2016 mitigations may not remove every failure.
If you would like KES to check affected PCs or manage Office updates across the business, contact the KES team.
