Microsoft has fixed a known issue that causes copy-and-paste failures for Excel users after installing the September 2026 security updates.
The bug was confirmed following a wave of customer reports on Reddit and the Microsoft Q&A forums that this month's updates (including the KB5002914 security update) break copy-and-paste, autofill, and formula dragging in Excel.
"In Microsoft Excel 2024, 2021, 2019, and 2016, as well as Excel Online in Office Online Server, the paste operation might fail silently," Microsoft explains in a support document updated on Friday.
"Although users try to paste content, the source remains selected and the destination is unmodified. When this issue occurs, users receive no indication of the failure, such as an error message or alert with sound."
To fix this known issue, affected users must manually download and install updates for Excel 2016 (KB5002665), Office LTSC 2019 (Build 10417.20208), Office LTSC 2021 (Build 14334.20918), and Office LTSC 2024 (Build 17932.21000).