To update from Azure Active Directory Sync to Azure AD Connect, see the upgrade instructions. Or is there an object that was deleted on-premises, but is stuck in the cloud?Take a look at this support article for guidance on how to resolve these issues.
To get started, in the classic admin center, under USERS, select Active Users, then select Set up.
In the admin center preview, under Users Active users, select Directory synchronization from the More menu on the Active users page.
Follow the instructions in the wizard to download Azure AD Connect.
If you are still using Azure Active Directory Sync (Dir Sync), take a look at How to troubleshoot Azure Active Directory Sync Tool installation and Configuration Wizard error messages in Office 365 for information about the system requirements to install dirsync, the permissions you need, and how to troubleshoot common errors.
With directory synchronization, you can continue to manage users and groups on-premises and synchronize additions, deletions, and changes to the cloud.
But setup is a little complicated and it can sometimes be difficult to identify the source of problems.
We have resources to help you hunt down potential issues and fix them.
You install Azure AD Connect through the Office 365 admin center.
Download the IDFix tool from the Microsoft download center.