Copilot in Excel not working? Check if your file is on Manual calculation

Why does Copilot in Excel need Automatic calculation?

First, some background on what calculation mode means. Normally Excel works out every formula again the moment a number it depends on changes, which is Automatic calculation and the default. On Manual, Excel waits, and your formulas only update when you press F9 or save the file. People switch to Manual when a workbook is so big that every small edit freezes the screen for a few seconds.

Microsoft’s Frequently asked questions about Copilot in Excel page lists this under the limitations of Copilot. It says “Copilot editing is only supported when Calculation Options are set to Automatic”. It does not explain why, so what follows is my own reading and not Microsoft’s.

Copilot writes formulas and then works with what they return. On Manual, a new formula can sit in the cell showing an old result until someone recalculates. An assistant checking its work against numbers that have not updated would be checking against the wrong thing, so blocking edits makes sense. It also matches the advice in my test for checking whether ChatGPT or Copilot got your Excel numbers right, because on Manual the numbers on your screen can be old for you as well.

Notice the exact word in the FAQ. It limits Copilot editing. Microsoft describes separate modes for Copilot, where chat mode analyses your data without changing the workbook, and edit mode makes the changes. So the rule is about Copilot changing your file, and I have not tested exactly what the pane shows on a Manual workbook.

Why is my workbook on Manual when I never changed it?

This is the part that confuses people, and it is the reason I am writing this. Microsoft has a support page called How Excel determines the current mode of calculation. Its first line says all open documents use the same mode of calculation, regardless of the mode they were saved in.

The rule works like this. The first workbook you open uses the mode it was last saved with, and every workbook you open after it uses that same mode. Microsoft’s own example uses two files. If you open Auto1.xlsx and then Manual1.xlsx, both run on Automatic, but if you open Manual1.xlsx first and then Auto1.xlsx, both run on Manual.

Picture a normal working day. Your finance team sends a large budget model that someone saved on Manual to keep it fast. You open it first to copy a figure, then you open your own report and ask Copilot to add a summary table. Your report was saved on Automatic, but it is running on Manual now because the budget model got there first, so Copilot is looking at a Manual session and will not edit.

The same thing happens with a template. Microsoft’s page says a new workbook made from a template takes the mode stored in that template. So if your company’s report template was saved on Manual, every report built from it starts on Manual too, and Copilot will refuse to edit all of them in the same way.

How do you switch Excel back to Automatic without breaking anything?

The switch itself is simple. In Excel for Windows or Mac, go to the Formulas tab, open Calculation Options and pick Automatic. You can also get there from File, Options, Formulas on Windows. In Excel for the web it is the same Formulas tab and the same Calculation Options menu, according to Microsoft’s page on changing formula recalculation.

That menu has a third option. Microsoft’s current page calls it Partial, and older pages call it Automatic except for data tables. It recalculates everything except data tables. The Copilot FAQ only names Automatic, so pick Automatic and not Partial when you want Copilot to edit.

But clicking Automatic changes more than one file. It is worth knowing what happens before you do it on a model that belongs to someone else.

The first thing comes from Microsoft’s recalculation page, which says changing these options in the Excel desktop apps affects all open workbooks. The second thing is the reason Manual exists at all. A model that someone put on Manual because it was slow will recalculate in full when you switch, and that can take a while.

The third thing catches people later. Microsoft’s page says that if the mode changed and the file is saved, the current mode is saved with it. If you switch to Automatic for Copilot and then save the colleague’s model, it will open on Automatic for them next time. The cleaner way is to close the Manual model before you work with Copilot, or open your own file first so the session starts on Automatic.

What else stops Copilot from editing an Excel file?

If calculation already says Automatic, the cause is one of a short list. Microsoft documents most of it. The trick is to match what you see on screen to the right cause, because “Copilot not working” covers very different problems.

If the file shows a message that says Unsupported file state, the FAQ gives two causes. The first is that the file is checked out in SharePoint, which is a setting where one person locks a file while they edit it. The FAQ says if your organisation requires check-out for editing, Copilot in Excel on Windows or Mac will not work for files from that site. The second cause is an unsupported format such as Strict Open XML Spreadsheet, and the fix is to save it as a normal Excel Workbook (.xlsx).

If there is no Copilot button at all, that is a different problem. Microsoft has a separate page for it, How to find and enable missing Copilot button in Microsoft 365 apps. It covers refreshing your licence from File, Account, Update License, and mentions the two privacy settings called Experiences that analyze your content and All connected experiences, and the update channel. Business users on the Semi-Annual Enterprise Channel need IT to move them to Current Channel or Monthly Enterprise Channel.

AutoSave used to be a blocker too, and a lot of older guides still say so. Microsoft’s What’s New in Excel for July 2026 says Copilot previously required AutoSave to be on, but now works in cloud-saved workbooks where AutoSave is turned off on Windows and Mac. If the workbook has unsaved changes, Excel reminds you to turn AutoSave on before Copilot starts making changes, but you can still carry on.

One more message is worth knowing. On Microsoft Q&A in August 2026, a user reported Copilot in the desktop app saying “Edit with Copilot is currently only supported in Excel for the web”. The answers there pointed at the Excel build and update channel, the licence, where the file is stored and the file format, and suggested opening the same workbook in Excel for the web as a test. That test is a good habit, because it tells you straight away whether the problem is the file or your Excel install.

What should you check first when Copilot in Excel is not working?

Most guides start with the licence, because that is the most common problem for someone who has never had Copilot working. But if Copilot worked yesterday and today it will not edit one particular file, the licence is the least likely cause. This is the order I would go in, from the fastest check to the slowest.

1. 01
   Look at Formulas, Calculation Options

   If it says Manual or Partial, pick Automatic. This takes five seconds and it is the cause the usual answers leave out.
2. 02
   Think about what you opened first

   If a big model or an old template was the first file open, close it or reopen Excel with your own file first, so you do not save a changed mode into someone else’s model.
3. 03
   Read the exact message

   Unsupported file state means check-out or file format. No button at all means licence, privacy settings or update channel. They have different fixes.
4. 04
   Save a copy as .xlsx and try that

   This clears the Strict Open XML case and tells you whether the problem is this one file or every file.
5. 05
   Open the same file in Excel for the web

   If Copilot edits it there, the file is fine and the problem is your desktop install, its build or its update channel.

Once Copilot is editing again, your work is not done. Anything it builds should get the same checks you would give a formula written by a new colleague. If you are moving away from the old in-cell function, my article on the COPILOT function being retired covers what the side pane can and cannot replace. And if the plan is to have Copilot rebuild the same weekly report every Monday, automating the Excel report itself is usually the more reliable route.