A critical bug in Microsoft’s September 2026 security update has been causing chaos for Excel 2016 users, leaving them unable to copy and paste data into their spreadsheets. The issue, which was first reported by affected customers on Microsoft’s Q&A forums and Reddit, was confirmed by the company earlier this week as a code regression that causes paste operations to fail silently.
The bug, caused by the KB5002914 update, affects not only Excel 2016 but also other versions of Excel, including Excel Online and versions from 2019 and later. However, Microsoft has released a fix specifically for Excel 2016 users in the form of update KB5002655. This patch resolves the copy-and-paste issue, which was making it impossible for users to paste content into their spreadsheets.
But here’s the catch: the fix only works on the .msi-based edition of Office 2016 and doesn’t apply to Office 2016 Click-to-Run editions, such as Microsoft Office 365 Home. This means that some users will still be affected by this issue until a permanent solution is available for all affected Excel versions.
To mitigate the problem in the short term, Microsoft recommends trying the “Paste Special” option, which can be accessed by selecting “Paste Special” from the “Paste” drop-down after opening the “Home” tab. This allows users to choose what type of data they want to paste into their spreadsheet, including formulas, values, and number formats.
Another temporary solution is to uninstall the KB5002914 security update, which will restore copy-and-paste functionality on impacted systems. However, this comes with a warning: uninstalling the update will also remove a long list of patches for remote code execution and information disclosure vulnerabilities.
In a bizarre twist, Microsoft has been dealing with a spate of issues related to its September updates in recent weeks. In June, the company addressed an issue that blocked Windows 365 users from downloading and installing the Office suite, as well as another one that prevented Office for the web users from opening Excel and PowerPoint files.
For now, affected Excel 2016 users are advised to be cautious when using their spreadsheets and to explore alternative methods of data transfer. In the long term, Microsoft will need to provide a permanent fix for all affected Excel versions to restore confidence in its security updates.
In the meantime, it’s essential for users to stay vigilant and keep an eye on any updates from Microsoft that may address this issue. By taking proactive steps to protect themselves from potential vulnerabilities, users can minimize their risk of falling victim to malicious attacks.
Source: Bleeping Computer — 2026-09-18