Forum Discussion

itls's avatar
itls
Copper Contributor
Jul 01, 2026

New Outlook Not Working if on Windows Insider

New Outlook not working after the Friday 6/26/26 Update. Multiple Ui control failures:

  1. Can open settings at first. Then would not open after.
  2. "X" to close not working
  3. New email not working
  4. File pull-down's not working

Starts out working fine. Settings, X-close, File menu. Then everything freezes when I do a email reply. No Settings, X-close, File menu.

I checked Copilot with above explaination. Response…Your description — Outlook starts out normal, but the moment you hit Reply the entire app freezes and all the chrome disappears (Settings, X‑close, File menu) — is classic Windows Insider Beta + New Outlook behavior. It’s almost always caused by a WebView2 runtime mismatch introduced by the last Windows update.

Copilot confirms...

You are on the affected Windows Insider build

OS build: 26220.8754

This is exactly the build where the WinUI window‑frame dispatch regression is documented.

That means:

✔ The issue is in Windows, not Outlook

✔ There is no local fix

✔ You must wait for Microsoft to patch the regression

✔ Rolling back to the previous Insider build does fix it

✔ Staying on 26220.8754 means Outlook’s “X” will not close the window

1 Reply

  • Jamony's avatar
    Jamony
    MCT
    Jul 02, 2026

    Hi, if this started right after an Insider build, I would treat it as a possible build regression. Test Outlook on the web first to confirm the mailbox is fine, then reset or repair the new Outlook app from Settings > Apps. If the UI controls still fail, capture the build number and Outlook version and file it through Feedback Hub. As a workaround, leaving the Insider build or switching temporarily to Outlook on the web may be the fastest path.