Microsoft has started looking into a problem that is preventing users from opening some Excel file attachments with non-ASCII file names in the new Outlook client for Windows. The issue has been affecting Exchange Online customers since late November, and many people are getting error messages when they try to open Excel files that are sent to them through email. The company is working on a solution, but in the meanwhile, it has advised workarounds.
The problem happens when Excel files have special characters in their names. These special characters could be things like accented letters, symbols, or characters from different languages that are not part of the basic English alphabet. When someone tries to open these files in the new Outlook, they get an error message that says “Try opening the file again later.” This message doesn’t really explain what’s wrong, which makes it harder for people to figure out how to fix the problem on their own.
Microsoft has already deployed a fix for this issue and explained that the root cause is an encoding error in how Excel file names are processed. The encoding error means that when the new Outlook client tries to read file names with these special characters, it can’t understand them properly. This causes the application to fail when it attempts to open the files. The company has tagged this incident as an advisory, which usually means the problem affects a limited number of users rather than everyone who uses the service.
According to Microsoft’s service alert, the issue specifically targets users who are working with Excel files that contain non-ASCII characters in the file name. ASCII refers to the standard American keyboard characters, so non-ASCII characters would include any letters, symbols, or marks that are not found on a typical American English keyboard. This means the problem could affect users around the world who work in different languages or who receive files from international colleagues and clients.
While Microsoft works on rolling out the fix to all affected users, the company has provided two simple workarounds that people can use to access their Excel attachments right away. The first option is to use Outlook on the web instead of the desktop client. When you open Outlook through your web browser, the web-based version processes these attachments correctly and doesn’t have the same encoding problem that the desktop client has. This means you can view and download your Excel files without any issues.
The second and the other workaround in which Microsoft suggests is to download the attachment to your computer first before trying to open it. Instead of clicking on the file to preview it directly in Outlook, you can save it to your local drive. Once the file is saved on your computer, you can open it directly in Excel without needing to go through Outlook at all. This bypasses the problem completely because the error only happens when Outlook tries to preview or open the file.
This incident joins a growing list of challenges that the new Outlook client has faced since Microsoft started pushing users to switch from the classic version. Many power users have complained that the new Outlook lacks some features that were available in the older COM-based application. The classic Outlook that many people have used for years had different capabilities and worked in different ways, and not everyone is happy about being forced to switch to the new version.
Microsoft has been encouraging users to move to the new Outlook as part of their plan to modernize their productivity apps and make everything work better together. However, issues like this Excel attachment problem show that there are still some technical challenges that need to be worked out. The company continues to release updates and fixes for the new Outlook to address these problems and improve the user experience.
For people who are affected by this issue, Microsoft recommends checking the Microsoft 365 admin centre under the reference ID EX1189359 to track the progress of the fix. System administrators can monitor when the fix will be fully rolled out to their organizations. The fix is currently being deployed across Microsoft’s infrastructure, and users should start seeing relief from this problem as the update reaches their systems.
Microsoft has not yet provided details about exactly how many users are affected by this encoding error or how long it will take for the fix to reach everyone. However, because the issue has been classified as an advisory rather than a critical incident, it suggests that the impact is relatively limited compared to other service disruptions. The company’s support team is available to help users who continue to experience problems even after the fix has been deployed.
This situation highlights the importance of thorough testing when companies release new versions of widely-used software. Email and productivity tools like Outlook are critical for millions of people who rely on them for daily work communication. When these tools don’t work properly, it can cause delays and frustration for users who are just trying to do their jobs. Microsoft will likely use this incident as a learning opportunity to improve how they test file handling in future updates to ensure similar encoding errors don’t happen again.
Microsoft has claimed that the update has not yet reached all affected customers, however users may need to restart the Outlook desktop program to properly resolve the issue after the patch has been implemented.