Our relationship to the Microsoft Partner Network allows us to provide competitive pricing and authentic software and support, all with a much-needed human element. On Windows, open Credential Manager, pick Windows Credentials, and remove anything related to Office 365 or Microsoft 365. For managed environments, we use Intune or Group Policy to force sign-in credential sync and clear old tokens.

• 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.
• After performing these steps, Outlook’s all folders will be synced to the server.
• This blog talks about the causes behind Outlook synchronization errors and a few solutions to fix Outlook sync issues.
• Check that your password change actually synced between your on-premises Active Directory and Microsoft Entra ID (formerly Azure AD).
• That tells us if the new credentials made it to the cloud directory.

Troubleshooting Microsoft 365 sync issues

At NetTech Consultants, we help organizations keep Microsoft 365 running smoothly and securely. The Users Loaded count will be 0 if all users fail to meet the system's requirements for user records. The Users Processed count will be 0 is there are no users in the synced dataset after filtering.

Common Reasons Behind Outlook Sync Issues

If the old password still works, the reset probably hasn’t synced. To resolve these issues you should run the steps in this article and check expert Outlook tips by FixTechGuide whether the groups in your sync's filtering preference contain users in Azure AD. 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.

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Keeping things updated helps avoid compatibility issues between on-premises Active Directory and Microsoft 365. If problems stick around, we rejoin the devices to Microsoft 365 services. Start by disconnecting the device from Work or School Account settings, then reconnect with the user’s updated password.

Get Expert Help from TrustedTech

If you're looking for smarter ways to manage, secure, or optimize your Microsoft 365 (M365) environment, our U.S.-based team is here to help. In these cases, direct escalation to Microsoft or working with a Microsoft CSP partner, such as TrustedTech, can expedite resolution and minimize downtime. Our licensing engineers can help triage complex problems and ensure you're on the right support path. Microsoft offers several built-in tools to help identify and resolve persistent issues. A vast community of Microsoft Office365 users that are working together to support the product and others. TrustedTech is dedicated to being a reliable resource for all software and technology support needs.

What should I do if my sync failed due to authentication issues?

We also scan Event Viewer logs under Applications and Services Outlook Stuck on Synchronizing Folders Logs → Directory Synchronization for Event IDs like 650–657 (for sync activity). Errors like Event ID 611 point to invalid replication data or outdated software. The error message in the Summary sheet of the Sync Summary spreadsheet attachment can also highlight the reason for this.

Troubleshooting Co-Authoring and Collaboration Errors

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.

To get the sync working you will either need to delete users or have the user limit on your account increased. Find out what to do if you are having issues with syncing users or groups from Microsoft 365. Real-time collaboration is at the core of Microsoft 365; however, issues can arise due to permissions, software version conflicts, or connectivity problems. There can be several reasons for the Outlook synchronization error. Before we know the solutions, we will understand a few common causes of the Outlook sync problem.



Users can also convert OST files into various file formats, including PST, HTML, EML, MSG, vCard, etc. It also provides the option to export the Outlook OST file into Office 365 and Live Exchange mailboxes. This software also has a splitter option to split large-sized PST files into smaller ones, helping users prevent oversized PST file issues. Incorrect Outlook settings can also be one of the reasons behind Outlook synchronization errors. We keep password synchronization reliable by staying proactive and making sure users know how their actions affect access across Microsoft 365 and their devices. If sync keeps failing, we make sure the Microsoft Entra Connect service account has the right permissions and the server connects to the domain controller.

We check that the Work or School Account in Windows Settings is active and linked to the right domain. The sync will fail if the groups you selected to load users from no longer exist in Azure AD. Typically this is because the selected groups have been deleted from Azure Exchange connectivity diagnostic AD since the M365 sync was configured on your account.