If someone in your office uses the new Outlook for Windows and suddenly can't open an attachment in Word, Excel, PowerPoint or Adobe Acrobat, they aren't alone. Since the last week of October, IT administrators have been reporting the same problem on Microsoft's own support forums, and some say it affects many of their users at once.
What people are seeing
The user opens an email, previews the attachment or right-clicks it, and chooses to open it in the desktop app. Then one of these happens:
- An "Opening file..." bar appears at the bottom of the window and disappears, and nothing opens.
- An error says the file can't be opened and suggests restarting Outlook. Restarting doesn't help.
- The file is saved to OneDrive and opens in the browser instead of the desktop app.
The same attachment opens fine in classic Outlook, in Outlook on the web, or after it's downloaded. That tells us the files themselves are fine. The break is in the hand-off from new Outlook to your desktop apps.
What seems to be causing it
The new Outlook is built on WebView2, a piece of Microsoft Edge that Windows keeps up to date on its own. The reports line up with WebView2 version 156, which arrived recently. One administrator found that two computers running the same Outlook behaved differently, and the only difference was the WebView2 version. Once the working computer picked up version 156, it started failing too. Another administrator showed that pointing Outlook back at the previous version, 155, made attachments open again.
The problem has been filed with Microsoft's WebView2 team. Microsoft engineers say they couldn't reproduce it on a newer build of the new Outlook and have asked for more details. As of today, Microsoft hasn't published an advisory or a fix, so treat the cause as likely but not yet confirmed.
Is your computer affected?
In the new Outlook, go to Settings > General > About Outlook. If the WebView2 version starts with 156 and attachments won't open in your desktop apps, you are probably seeing this issue.
Workarounds for now
- Download, then open. Download the attachment and open it from your Downloads folder. This is the quickest fix for most people.
- Switch to classic Outlook. If your organization still allows it, use the toggle at the top of the new Outlook to go back to classic Outlook until a fix arrives.
- Use Outlook on the web. Sign in at outlook.office.com and open the attachment there.
- Update the new Outlook. Microsoft tested on a newer build and didn't see the problem. Updating won't hurt and may help, but we haven't seen it confirmed as a fix.
- Report it. In the new Outlook, choose Help > Feedback > Report a problem. The more reports Microsoft gets, the sooner it gets attention.
There is also a technical workaround that forces the new Outlook to use the older WebView2 version. It works, but it means running an older component that stops getting security updates, so we'd only use it for a short time and undo it once Microsoft ships a fix.
How we can help
If this is slowing your team down, we can confirm whether your computers are affected, set up the simplest workaround for your office, and keep an eye out for Microsoft's fix so we can roll it back cleanly. Contact us or call (480) 382-3289.
Sources: New Outlook Will Not Open Attachments in Desktop Apps (Microsoft Q&A); Outlook New doesn't open desktop Microsoft apps (Microsoft Q&A); WebView2 Runtime 156.x prevents New Outlook attachments from opening (Microsoft WebView2 feedback on GitHub)