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BusyCal Unable to Connect to Outlook Personal Accounts / Office 365

Troubleshoot a connection problem​

For setup and authentication help, use the guide for your device:

A connection error today does not establish that the historical incident below is still occurring. Check the exact error and Microsoft's service status. You can also check your calendar through Outlook on the web.

Historical incident: May 27, 2025​

This article originally described reports from May 27, 2025, when some Outlook.com, Live, and Hotmail personal accounts returned HTTP 500 errors while third-party applications requested calendar data. The reports below document that incident; they are not a live service-status notice and do not establish its current status.

Reported symptoms​

The May 2025 reports included HTTP 500 errors, a “Could not fetch container collection” message, calendars failing to refresh, and failures when adding personal Outlook accounts. Similar symptoms can have other causes; authentication failures or organizational Office 365 account problems should be checked against the connection guides above.

If you see a server error​

Try again later and check Microsoft's service status. If the error persists, contact support with the exact error message, when it occurred, your BusyCal version, and whether the account is personal or managed by an organization. Do not include your password.

Access your calendar on the web​

If the calendar is available in Outlook on the web, you can use it there while investigating the BusyCal connection. Switching to Microsoft Graph is setup guidance for an older connection, not a confirmed workaround for a Graph server error.

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