Microsoft’s Excel security patch breaks copy-paste across versions, with no quick fix yet
Microsoft confirms a bug in the September 2026 Excel security update KB5002914 that silently breaks copy-paste across Excel 2016–2024, with Microsoft investigating and no official fix yet. Workarounds include Paste Special, using Word as an intermediary, the Office Clipboard, or rolling back the update (not advised due to 29 security fixes). The issue is widespread across supported Excel versions and comes amid broader Windows 11 update problems.