Microsoft is currently working on a solution to fix an issue affecting Outlook for Microsoft 365 customers, preventing them from accessing emails and their calendars. According to a support document, users may be unable to view or access Microsoft 365 group calendars and email messages in Outlook Desktop, after updating to Outlook Version 2303.
This buggy version was released to the Current Channel on March 28 and is impacting some users when trying to add or access the group mailbox or calendar, change mail items, or add, remove, or edit group members.
Although some affected users may notice that the impact self-resolves after some time, others may experience the issue again at a later time. However, Microsoft has shared a temporary workaround until a fix is rolled out.
Affected customers are advised to use Outlook Web Access (OWA) if they want to use the Groups feature or revert to Outlook Desktop build 16130.20332, which is not affected by the issue.
To revert to the previous unaffected Outlook build, the detailed procedure requires opening a Command Prompt (Run as Administrator) and typing or pasting some commands. The Outlook Team is working on a solution to address this known issue, and the fix is expected to be released on Patch Tuesday on May 9, 2023.
Until then, customers may use the temporary workaround to access their emails and calendar in Outlook. Microsoft also fixed a sign-in issue preventing customers from accessing their account since October 2022 in the same buggy Outlook version.