You can close the wizard at this point as you do not need to complete it for re-authentication to take effect. You should run a test sync after re-authenticating the sync to ensure it is working. Now, we will verify the server settings to fix the Outlook synchronization error. The sync will fail if the groups you selected to load users from no longer exist in Azure AD.

Common Causes of Sync Issues in Outlook

Typically this is because the selected groups have been deleted from Azure AD since the M365 sync was configured on your account. Outlook’s ability to connect to the mail server may be blocked by firewalls or antivirus software. After you’re satisfied, turn off your firewall or antivirus program for a while. If it does, you might need to include Outlook exceptions in the settings of your security program. After viewing, see fixing problems with directory synchronization for Microsoft 365 to correct any identified issues. After performing these steps, Outlook’s all folders will be synced to the server.

Fixing problems with directory synchronization for Microsoft 365

Sync failure alerts do not always include a full summary or attachment, you can run a test sync to obtain this data. The other solution to fix Outlook sync issues is recreating Microsoft Outlook profile. Incorrect Outlook settings can also recreate Outlook profile step by step be one of the reasons behind Outlook synchronization errors. So, follow the below steps to reset Microsoft Outlook settings. The M365 sync establishes a synced dataset based on your M365 data and the filtering configuration of your sync.

• Before we know the solutions, we will understand a few common causes of the Outlook sync problem.
• This blog talks about the causes behind Outlook synchronization errors and a few solutions to fix Outlook sync issues.
• The Support and Recovery Assistant, a tool provided by Microsoft, can identify and resolve common Outlook problems.
• Find out what to do if you are having issues with syncing users or groups from Microsoft 365.
• Typically this is because the selected groups have been deleted from Azure AD since the M365 sync was configured on your account.
• The simplest way to resolve authentication issues is to rerun the authentication process by clicking the Sign in with Microsoft on the Microsoft 365 settings page.
• Moreover, it maintains the folder hierarchy and metaproperties of the data when processing Outlook data files.

Use the Microsoft Support and Recovery Assistant

Outlook sync issues can be because of corrupted Outlook OST or PST files. Therefore, now we will know the steps to repair the Outlook data file. The most common reason for missing users is that you've run a Test Sync, instead of a Manual Sync. If that doesn't resolve your missing users issue, please follow our guide to troubleshooting missing users below. With directory synchronization, you can continue to manage users and groups on-premises and synchronize additions, deletions, and changes to the cloud.

How to Fix Outlook Sync Issues in Windows?

The sync will fail if it can't find any users that comply with your filtering preferences or the system's requirements for user records. The system requires that users have a first name, last name and a valid email address that conforms with your domain lock if enabled. The sync does not delete users but rather sets them to inactive. The idea is to provide a flush DNS and re-sync Outlook recycle bin of users who you can delete when you no longer need them.

Mailing Address

You can view your inactive users on the Users page and delete them as you see fit. Similarly you should review FixTechGuide Outlook repair tutorial the Users Deactivated sheet on the sync summary spreadsheet attachment as you can also delete these users to bring your total down. I have multiple users experiencing sync errors with Outlook and office365.

What should I do if my sync fails because it can't find any users?

The error message in the Summary sheet of the Sync Summary spreadsheet attachment can also highlight the reason for this. This means that the authentication setup for your sync is no longer valid. This can happen for the a number reasons particularly if your sync authenticates using Delegated Permissions.



This blog talks about the causes behind Outlook synchronization errors and a few solutions to fix Outlook sync issues. We have shared five manual methods in this blog to resolve the Outlook syncing errors. Apart from this, we also discuss the Shoviv OST to PST Converter Tool, a professional way to repair, recover, and convert Outlook data files. This solution will be beneficial for users who are facing Outlook syncing issues because of corrupted PST or OST files. Users can also try its free demo version in their system and process the first 50 items from each folder freely. Always make sure your profile and settings are set up correctly, your software is up to date, and your connection is steady.