When you use Copilot in Excel for the web while another person is editing the same workbook, suggestions from Copilot can conflict with changes made by your co-author. This happens because Excel Web’s co-authoring engine and Copilot’s suggestion model operate on different update cycles. This article explains why these conflicts occur, how Excel and Copilot handle them, and what you can do to avoid losing work.
Key Takeaways: Managing Copilot Suggestions During Co-Authoring
- Excel Web co-authoring conflict resolution: Excel automatically merges changes and shows a yellow banner when a conflict occurs.
- Copilot suggestion model: Copilot generates suggestions based on the workbook state at the moment you request it, not after co-author changes are saved.
- Manual acceptance workflow: You must review and accept or reject each Copilot suggestion before it becomes a permanent change.
How Co-Authoring and Copilot Interact in Excel Web
Excel for the web supports real-time co-authoring. When two or more people edit the same workbook simultaneously, Excel syncs changes every few seconds. Each person sees the other’s edits as they happen, but only if both are using the web version. The co-authoring system uses a technique called conflict-free replicated data types, or CRDTs, to merge most edits automatically. Formula changes, cell value updates, and formatting adjustments merge without issues in most cases.
Copilot in Excel for the web works differently. When you click the Copilot button and ask for a suggestion, Copilot reads the current state of the workbook from the server. It does not read changes that your co-author has not yet saved. If your co-author modifies a cell range that Copilot uses to generate a suggestion, the suggestion may reference outdated data. This is the root cause of suggestion conflicts during co-authoring.
What Happens When a Conflict Occurs
Excel detects a conflict when Copilot tries to apply a suggestion that modifies a cell or range that another user changed after Copilot read the workbook state. Excel shows a yellow banner at the top of the worksheet with the message: “A conflict occurred. Review the changes.” The conflicting suggestion is not applied automatically. Instead, Excel preserves both the co-author’s changes and the Copilot suggestion as a pending action. You must decide which version to keep.
Steps to Handle a Copilot Suggestion Conflict in Excel Web
Follow these steps to resolve a conflict between a Copilot suggestion and a co-author’s edit.
- Identify the conflict banner
Look for a yellow banner at the top of the worksheet. It says “A conflict occurred. Review the changes.” Click the Review button inside the banner. - Open the conflict resolution pane
Excel opens a side pane titled Conflicts. This pane lists each conflicting cell or range. Each entry shows your Copilot suggestion and the co-author’s change side by side. - Choose which version to keep
For each conflict entry, click Accept Mine to keep the Copilot suggestion or Accept Theirs to keep the co-author’s change. You can also click Accept All Mine or Accept All Theirs at the top of the pane to resolve every conflict at once. - Save the workbook
After you resolve all conflicts, click File then Save or press Ctrl+S. This commits your choices to the server and clears the conflict state. - Verify the final data
Check the affected cells to confirm that the correct values are present. If you accepted the Copilot suggestion, verify that the formula or value matches what you expected.
Preventing Conflicts Before They Happen
You can reduce the chance of suggestion conflicts by coordinating with your co-authors. Ask them to avoid editing the same rows or columns that you plan to modify with Copilot. If you need to use Copilot on a shared range, ask your co-author to pause editing for a few seconds. You can also use the Refresh button in the Copilot pane to reload the workbook state before generating a suggestion.
If Copilot Suggestions Still Conflict After Resolution
Even after you resolve one conflict, new ones can appear if your co-author continues editing. Here are the most common follow-up problems and how to fix them.
Copilot Suggestion References a Deleted Range
Your co-author deleted a column or row that Copilot used in its suggestion. The suggestion formula shows a #REF! error. To fix this, discard the suggestion by clicking the Undo button or pressing Ctrl+Z. Then ask Copilot to generate a new suggestion after your co-author finishes their edits.
Copilot Suggestion Overwrites a Co-Author’s Formula
You accepted a Copilot suggestion that wrote a formula into a cell where your co-author had already entered a different formula. The conflict pane shows both formulas. Review the logic of both formulas. If the co-author’s formula is correct, accept their version. If the Copilot formula is correct, accept yours. Then notify your co-author about the change so they can update their dependent cells.
Copilot Suggestion Creates a Duplicate Named Range
Copilot sometimes creates a named range as part of a suggestion. If your co-author created a named range with the same name in the same workbook, Excel shows a conflict. Open the Formulas tab and click Name Manager. Rename one of the duplicate ranges. Then re-run the Copilot suggestion.
Copilot Suggestion Behavior: Co-Authoring vs Single-User Editing
| Item | Co-Authoring (Excel Web) | Single-User Editing (Excel Web) |
|---|---|---|
| Conflict detection | Excel detects when Copilot modifies a cell changed by another user | No conflict detection needed |
| Conflict resolution UI | Yellow banner + Conflicts pane with Accept Mine / Accept Theirs | Not applicable |
| Suggestion generation latency | Copilot reads workbook state at request time; co-author changes may not be included | Copilot reads the latest saved state |
| Auto-apply behavior | Suggestion is not applied until you accept it in the Conflicts pane | Suggestion is applied immediately after you click Apply |
| Undo behavior | Undo reverses the last accepted conflict resolution, not individual cell changes | Undo reverses each applied suggestion step by step |
| Recommended workflow | Coordinate editing ranges with co-authors; refresh Copilot before each suggestion | No special workflow needed |
You now understand how Copilot suggestion conflicts occur during co-authoring in Excel for the web and how to resolve them. Next time you work with a colleague, open the Conflicts pane immediately if you see the yellow banner. For a smoother experience, assign separate worksheet tabs to each co-author so Copilot suggestions and manual edits do not overlap. If you frequently encounter conflicts, try using the Excel desktop app instead, which uses a different co-authoring sync model that reduces suggestion conflicts.