Microsoft confirms KB5002914 Excel update breaks copy and paste
Microsoft has confirmed that copy and paste may silently fail for some Excel users after installing the September 2026 KB5002914 security update.
Microsoft has confirmed that copy and paste may silently fail for some Excel users after installing the September 2026 KB5002914 security update. This follows a wave of customer reports on Reddit and the Microsoft Q&A forums that the KB5002914 Office security update is breaking copy-and-paste , autofill, and formula dragging in Excel. The company has confirmed these issues, saying they affect Microsoft Excel 2024, 2021, 2019, and 2016. "Although users try to paste content, the source remains selected and the destination is unmodified," Microsoft said in an updated support document .
One month earlier, Microsoft addressed another bug that blocked Office for the web users from opening Excel and PowerPoint files, and another that blocked Windows 365 users from downloading and installing the Office suite.
What changed
In July, Microsoft also fixed an issue that was preventing third-party applications from launching Word, Excel, PowerPoint, Access, and other Microsoft Office apps or opening documents on up-to-date Windows systems.
On Monday, it also released emergency out-of-band updates to resolve Remote Desktop Services failures caused by the September 2026 security updates, along with Hyper-V and USB audio problems on some Windows versions.
Who is affected
One month earlier, Microsoft addressed another bug that blocked Office for the web users from opening Excel and PowerPoint files, and another that blocked Windows 365 users from downloading and installing the Office suite.
What to watch next
Watch for revised fixed-version guidance and confirmation that mitigations are holding in affected environments.
What remains unknown
The available reporting does not establish whether the issue is being actively exploited in the wild.
The available reporting does not establish who is behind the activity, if an attacker is involved.