Hello @XYA-9477
This appears to be related to the recent Excel 2016 security update KB5002914, rather than a normal Excel clipboard or keyboard configuration issue.
Multiple reports describe the same behavior after the September 2026 updates: Ctrl+C/Ctrl+V stops working for Excel cells, while copying text from applications such as Word into Excel can still work. Some users have also reported problems with dragging/filling cells and copying worksheets.
A related Microsoft Q&A thread specifically identifies KB5002914 as the suspected update. Users there reported that rolling back/removing the patch restored Excel copy/paste functionality. The original poster also confirmed that removing the problematic update resolved the issue.
Since your issue started around September 9, first check whether KB5002914 was installed on the machine around that date.
I do not recommend replacing Excel.exe with a copy from another PC, even though that workaround has been mentioned in the other thread. For a managed/business PC, it would be safer to have the administrator test removal/rollback of KB5002914 and temporarily prevent it from being reapplied while waiting for Microsoft to address the regression.
To remove the update, open the Command Prompt as administrator and run the following command: "C:\Program Files\Common Files\Microsoft Shared\OFFICE16\Oarpmany.exe" /removereleaseinpatch "{90160000-0012-0000-1000-0000000FF1CE}" "{27882596-A8ED-4382-9C71-6CD2DD19F732}" "1033" "0"
Also, since you mentioned that Ctrl+A while editing a cell was already broken before this update, that may be a separate issue and shouldn't necessarily be attributed to KB5002914.
Related thread with users reporting the same problem:
Issue with Excel 2016 – copy and paste cells | Microsoft Q&A
At this point, reports strongly suggest a regression associated with the September Excel 2016 update, although Microsoft has not officially confirmed it as a known issue.
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