Microsoft says it’s still investigating a known issue that causes the Copilot and Copilot Chat buttons in classic Outlook to disappear for some Windows users.
As it acknowledged when it announced a fix via a service change in June, this affects only customers with the Copilot Chat (Basic) license or a paid M365 Copilot (Premium) account who may no longer see the Copilot buttons in the side navigation and above the ribbon.
According to Microsoft, affected users may also experience one or more of the following issues:
- The Copilot button is missing from the top-right area above the ribbon.
- The Copilot icon is missing from the left app bar or More Apps area in classic Outlook.
- In Add Apps, Copilot may appear as an available app, but selecting Open does nothing.
- Adding Copilot through ribbon customization may show the command as unavailable or grayed out.
- Copilot remains available from other entry points, such as Outlook on the web or the Microsoft 365 Copilot standalone app or web experience.
However, in a recent update, Microsoft said it’s still investigating the issue and confirmed it happens after upgrading classic Outlook for Windows to build 20026.20182 and higher.
“The Outlook Team is actively investigating this issue. Current analysis indicates that, in affected environments, Outlook is unable to locate the MAPI property PR_PROFILE_USER_SMTP_EMAIL_ADDRESS_W within the null profile section,” Microsoft said.
“As a result, the Outlook Copilot component cannot persist in Copilot-related settings, which may prevent the Copilot entry point from appearing in the Outlook navigation pane.”
While it’s still working on a permanent fix, Microsoft has shared a temporary workaround that requires enabling the “Show Apps in Outlook” option in classic Outlook settings.
To do that, select the File tab, then Options, go to Advanced, and check the box for “Show Apps in Outlook” under “Outlook panes,” as shown in the image below.
Affected users can also create a new Outlook profile or use the new Outlook email client or Outlook Web Access (OWA), which are not affected by this bug.
Microsoft has also confirmed a bug that causes unexpected Outlook crashes on systems running Kaspersky Antivirus software, triggering “Event 1000” events in the Application log linked to the Kaspersky Mail Checker (mcou.dll).
Although the Outlook Team is still investigating, it advised Kaspersky customers experiencing crashes to contact Kaspersky support.
Earlier this year, Microsoft also resolved known issues that rendered the classic Outlook client unusable when enabling the Microsoft Teams Meeting Add-in and prevented some classic Outlook users from sending emails via Outlook.com.
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