Microsoft says Copilot buttons still missing in classic Outlook
Summary
Microsoft is investigating a bug where Copilot buttons disappear in Classic Outlook for Windows users with Copilot Chat (Basic) or paid M365 Copilot (Premium) licenses, particularly after updating to build 20026.20182 and higher. The issue stems from Outlook being unable to locate a specific MAPI property (a data structure that stores email settings) needed to display the Copilot feature in the navigation pane. Copilot remains accessible through other entry points like Outlook on the web or the Microsoft 365 Copilot standalone app.
Solution / Mitigation
Microsoft has shared a temporary workaround: enable the "Show Apps in Outlook" option by selecting File > Options > Advanced and checking the box for "Show Apps in Outlook" under "Outlook panes." Affected users can also create a new Outlook profile, switch to the new Outlook email client, or use Outlook Web Access (OWA), which are not affected by this bug.
Classification
Affected Vendors
Related Issues
Original source: https://www.bleepingcomputer.com/news/microsoft/microsoft-shares-workaround-for-missing-outlook-copilot-buttons/
First tracked: September 16, 2026 at 02:01 PM
Classified by LLM (prompt v3) · confidence: 75%