Although Microsoft puts a great deal of effort into refining and optimising its software, the truth is that its products are not immune to disruptive bugs. Windows is a clear example—patches released to fix issues occasionally introduce new ones.
And now, according to a report from BleepingComputer, a new problem has surfaced, this time affecting Outlook.
A new Outlook bug prevents users from opening Excel attachments
Outlook, Microsoft’s flagship email client and a direct competitor to Gmail, receives frequent updates that add features and enhance performance. Even so, as with any complex software, issues can still slip through.
Recently, Microsoft acknowledged a particularly inconvenient bug in the new Outlook client: users were unable to open Excel attachments. For many, this is a serious inconvenience, especially in work environments where Excel files are essential.
According to BleepingComputer, the issue has been impacting Exchange Online users since November 23, 2025. Microsoft has since released a fix and confirmed that the problem stemmed from the file names of the Excel attachments. Specifically, attachments containing non-ASCII characters—such as accented letters or certain symbols—triggered an error message prompting users to “try opening the file later.”
Microsoft has not shared many additional technical details, but the root cause appears to be tied solely to the naming of the files, not the files themselves.
Now it’s just a matter of waiting for the patch to roll out to everyone affected. Even so, it’s reassuring to see Microsoft moving quickly to address issues like this, continuing the company’s recent trend of responding more proactively to problems within its platforms and applications.
