Microsoft is investigating a known issue that affects Microsoft 365 customers and causes classic Outlook to hang or freeze when copying text.

These problems appear on systems running Outlook Current Channel Version 2409 (Build 18025.20096) or higher or when using languages with an IME (Input Method Editor).

"When you select text in a classic Outlook email and then use the copy shortcut Ctrl+C, Outlook may hang or freeze," Microsoft explains. 

Redmond says its Outlook team is investigating this newly acknowledged issue and will provide more info when mitigation measures or a fix are available. Until a solution is found, the company offers affected customers several temporary fixes to work around the issue.

They can revert to a previous Input Method Editor version using the detailed instructions available on the Revert to a previous version of an IME support page.

This requires opening the Settings app, searching for "IME settings," selecting their language's IME settings, clicking General, and enabling the "Use previous version of Microsoft IME" option.

Microsoft also advises those impacted to revert Outlook to the previous build, which isn't affected by this known issue.

To do that, search for Command Prompt in the Windows search box, right-click the "Command Prompt" icon, and click Run as administrator. Next, you paste the following commands in the Command Prompt window that shows up and hit Enter after each:

In September, Microsoft also fixed a bug that crashed Microsoft 365 apps like Outlook, Word, Excel, and OneNote when typing or spell-checking a text.

One month earlier, the company shared temporary workarounds for more known issues, including one that triggered Gmail sign-in issues for classic Outlook users and caused Outlook to crash after opening.