October 29, 2026: Some New Outlook for Windows users canāt open email attachments after an Microsoft Edge WebView2 Runtime 156.x update. The Register reported that Microsoft has begun rolling out a fix. For now, you can save a trusted attachment and open it in File Explorer. Verify unexpected messages with the sender before opening their files; saving an attachment does not make it safe.
What Happened
The Register says Microsoft issued service advisory EX1528992 on October 28. An unnecessary setting enabled with Edge WebView2 156.x disrupted attachment opening in New Outlook for Windows. The attachmentās Open option may disappear. Outlook may also say it canāt open the file and ask you to restart.
The Register says Microsoft began rolling out a settings fix on October 29 and expected deployment to take 12 hours. That was an estimate, not confirmation that every affected PC has received it.
In Microsoftās WebView2 issue tracker, Microsoft engineer Ojasvi Das said on October 29 that the team had identified the cause and was rolling out a fix in the current stable version. His estimate was another six to seven hours, followed by relaunching the app. In a later comment in the same thread, Das clarified that this fix uses a kill switch on the same runtime, deployed differently from a runtime update through Edge Updater. Neither comment confirms completion for every user.
The issue affects opening attachments in the app. The Register describes opening failures and does not report attachment or content loss.
How It Stacks Up
The reported scope is narrow: New Outlook for Windows is the affected app, and Edge WebView2 156.x is the linked component. The evidence doesnāt show that every Edge 156.x, WebView2 156.x, or Outlook installation has the problem. The Register says Classic Outlook did not appear to be affected.
| Option | What the evidence supports | Trade-off |
|---|---|---|
| Save As, then File Explorer | The Register reports this as a workaround while Microsoftās settings fix rolls out. | Adds a save step while opening it in the app is broken. |
| Classic Outlook | The Register says it did not appear to have the same issue. | Requires another Outlook app where available. |
| Outlook on the web | A Microsoft Q&A discussion describes desktop-opening failures; user reports in the WebView2 issue tracker say downloading or opening in a browser worked for them. | May offer another access route; not confirmed for every affected attachment and does not repair New Outlook. |
| Wait for Microsoftās settings fix | The Register says the rollout began October 29. Youāll need to restart New Outlook after the fix arrives. | The reported 12-hour estimate is not a guarantee for each PC; completion remains unconfirmed. |
Users in the Q&A and WebView2 issue tracker report failures with WebView2 156.0.4314.42 and 156.0.4314.50, while 155.0.4283.62 worked in their comparisons. Those observations do not establish a supported way to roll back. Results can reportedly vary between machines even when they appear to run similar software versions.
Iād skip uninstalling Edge or manually downgrading WebView2 for now.
The Reaction
This article doesnāt include verified posts from X, Reddit, or Hacker News. As a result, it doesnāt reflect how users on those platforms are reacting to the update.
Our Take
Verdict: Save the attachment while Microsoftās fix rolls out. For attachments you trust, use Save As, then open the file in File Explorer. Verify unexpected messages with the sender before opening their files, and scan downloaded files with your security software. Microsoftās Outlook attachment help page covers attachment problems in general. For this issue, The Register reports that Microsoft is rolling out a settings fix.
Close and reopen New Outlook to check whether the fix has reached your installation, then try a trusted attachment again. Restarting is not proof the fix has arrived.
Administrators can check Microsoft 365 Service health for advisory EX1528992 for updates on the rollout. The rolloutās completion and the number of affected users remain unconfirmed.