Microsoft has confirmed that the September 2026 security update for Excel (KB5002914) introduced a bug that prevents users from performing standard copy and paste operations. The issue is characterized by its “silent” failure; when a user attempts to paste data, Excel provides no error message or notification, and the destination cell remains unchanged despite the source selection remaining active.
The bug, which was part of the Patch Tuesday release on September 8, 2026, is not limited to the standard Ctrl+C and Ctrl+V commands. Users have reported that the “fill handle” for dragging formulas, the AutoFill functionality, and the ability to copy entire worksheets are also currently broken. Microsoft officially acknowledged the reports on September 10, 2026, stating that the company is researching the issue.
Affected Excel Versions
While KB5002914 is the specific identifier for the Excel 2016 MSI update, the underlying defect has been observed across several versions of the spreadsheet software. The following versions are confirmed to be impacted:
- Excel 2016 (MSI and Click-to-Run)
- Excel 2019
- Excel 2021 LTSC
- Excel 2024
- Microsoft 365 Apps
The silent nature of the failure presents a risk for data integrity. Because Excel does not produce a beep or a warning dialog, users may mistakenly assume a paste operation was successful, leading to potential errors in large datasets or complex financial models.
Technical Workarounds and Rollback Steps
Microsoft has not yet released a definitive patch to resolve the “silent paste” bug. In the interim, the only verified method to restore functionality is to roll back the Office installation to a version prior to the September 8 update.
Users should be aware that rolling back involves a security tradeoff. KB5002914 includes several patches for remote code execution (RCE) vulnerabilities. Uninstalling the update for productivity reasons will re-expose the system to those specific security flaws.
For users on Click-to-Run versions (including Microsoft 365 and Excel 2021), functionality can be restored by reverting to build 16.0.20326.20132. This is done via the command prompt:
1. Open the Command Prompt as an Administrator.
2. Enter the following command for Microsoft 365 or Office 2021:
"C:\Program Files\Common Files\microsoft shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.20326.20132
For users on the Excel 2016 MSI version, the update can be uninstalled through the traditional Windows interface:
1. Open Control Panel > Programs > Programs and Features.
2. Select View Installed Updates.
3. Locate Security Update for Microsoft Excel 2016 (KB5002914), right-click it, and select Uninstall.
After performing a rollback, it is recommended to temporarily disable automatic updates in Excel (File > Account > Update Options > Disable Updates) to prevent the system from re-applying the faulty patch until Microsoft releases a permanent fix.
