In some cases, you’ll see the following error message during the installation of Easy365Manager:
The Active Directory schema is extended with multiple Exchange-specific attributes when you install Exchange on-premises. Some of these attributes are a vital part of mailbox management on linked accounts (Office 365 accounts that are synchronized from your local AD).
If you want to use Easy365Manager to manage Office 365 mailboxes and licenses as an integral part of your AD user management, your local AD must be updated with the Exchange schema extension.
You don’t need an Exchange on-premises server installation, only the Active Directory schema update.
To confirm if the Exchange schema extension is missing from your domain, run the script in this article. If the Exchange schema version is less than 14726, you must update your schema with the Exchange schema extension.
How to Fix This Error
To update the Active Directory schema with the Exchange schema extension, download Exchange and run the schema extension.
Download Exchange 2016 CU22 here.
Mount the iso file and run the following command from the mounted drive:
Setup.exe /PrepareSchema /IAcceptExchangeServerLicenseTerms
Refer to the official documentation from Microsoft for more information on extending the Active Directory schema with the Exchange schema extension.
After extending your AD schema, you must reload the schema in Azure AD Connect.
Open up Azure AD connect, click Configure and select Refresh directory schema:
Once the directory schema refresh has been completed, you can rerun the Easy365Manager installation.