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.

“Although users try to paste content, the source remains selected and the destination is unmodified,” Microsoft said in an updated support document confirming these issues.