Microsoft retires Excel's =COPILOT() on Sept 14 — it never hit GA
Microsoft is pulling its LLM-in-a-cell formula and pushing users to the Copilot side pane — a quiet retreat from a feature it warned not to trust for real work.
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The =COPILOT() formula is gone on Sept 14
Microsoft's message-center notice MC1454373 (posted Aug 15) sets a Sept 14, 2026 shutdown for the in-cell =COPILOT() function. It spent over a year in preview with Frontier and Insider users and never reached general availability — so anything you prototyped on it stops working next month.
Where your cells go instead
There's no drop-in replacement formula. Microsoft points you to the Copilot side pane and the floating Dynamic Action Button for the same summarize, classify, generate and web-lookup tasks, now with multi-agent web search. All still need a Microsoft 365 Premium/Copilot license and a live connection.
Microsoft already told you not to trust it
Even while shipping it, Microsoft warned =COPILOT() off numerical calculations, pulling values already stored in your workbook, and anything under legal or compliance rules. Retiring a feature it framed as unreliable is a quiet signal that 'an LLM in every cell' didn't pan out.