Troubleshoot Calendar Interop issues

Follow these troubleshooting steps if you have issues with Calendar Interop.

Issue	Explanation & resolution
When trying to check a Google Workspace user's availability, Microsoft Exchange or Exchange Online (Microsoft 365) users get an error message the user is not found. Other Google Workspace user accounts work as expected.	Ensure the custom contact created for the Google Workspace user in the Exchange or Exchange Online environment has mail turned on.
Google Workspace users can check the availability of some Exchange users, but not others.	Calendar Interop requires email addresses of Exchange users are not in use by Google users, either as part of the Google Workspace domain or as a consumer account. If availability (free/busy) lookups work only for some accounts and not others, the likely explanation is not a Calendar Interop configuration issue. It's probably the existence of the Exchange account in Google. Corrective actions: In the Google Admin console, search for the email address. If you find it there, make sure the user is in an organizational unit where Google Calendar is turned off. Check the transfer tool for unmanaged (consumer) users, where you can resolve the conflicting account. If the account exists in Google Workspace, but you want to use Calendar Interop for the same account, you can temporarily move the Google Workspace account to an organization where Calendar is turned off.
Exchange users can't check the availability of Google Workspace users.	Run a test using the user availability lookup tester tool. The tester tool requests a user's availability using Exchange. If a Google Workspace email address is entered, Exchange requests availability from Google Workspace. If an Exchange email address is entered, Exchange retrieves the Exchange user's availability. The tool also shows detailed error messages Exchange encounters. You must be signed in as a super administrator for this task.
Google Workspace users can't check the availability of Exchange users.	Run a test using the user availability lookup tester tool by entering an email address of an Exchange user. This step asks Exchange to resolve the availability of the user. You should get a detailed error message there. You must be signed in as a super administrator for this task. If there's no error in the availability (free/busy) tester tool, the Google Calendar web interface might still display the wrong information. There are several possible symptoms, for example: The user appears as busy when they're marked as available on Exchange The user appears as available when they're marked busy on Exchange The error message "Calendar cannot be shown" is displayed The most common cause for these symptoms is a Google Workspace user or Google user has Google Calendar turned on.  ​Check to make sure Google Calendar service is turned off for this user (even if it's a user in a different Google Workspace account).
Event detail feature is turned on, but Exchange users only receive availability blocks of Google Workspace users.	Verify the Google role account or accounts you selected can access the required calendars and event details. Sign in to the account in Google Calendar and try to access the Google Calendar for which details don't appear in Microsoft Outlook. Make sure you can view the details in Google Calendar. You might be using an old Calendar Interop authentication setup, which only allows accessing availability data. To fix this, regenerate Exchange credentials using the Exchange authentication credential generation tool. Then update your availability address space using the Exchange server configuration tool. For details, go to steps 3 through 5 in Allow Exchange users to see Calendar availability data.
Event detail feature is turned on, but Google Calendar users only get availability blocks of Exchange users.	Verify the Exchange role account or accounts you selected can access the required calendars and event details. Sign in to the account in Outlook and try to access the Exchange calendar for which details don't appear in Google Calendar. Make sure you can view the details in Outlook.

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