Both of our authentication methods can fail if the Enterprise Applications entry for the sync in Azure AD is deleted or if it has had its permissions modified. We go above and beyond the average software reseller because we built our business on trust. As active members in the IT community, we work to support our clients’ businesses and provide them with peace of mind. After these instructions, ensure the sync settings are correct and check everything is working well. For managed setups, we can push a PowerShell script with Intune or Group Policy to clear cached tokens on all devices. A quick look at the Microsoft Entra Connect Health portal helps us see if sync tasks are current and the connection to Microsoft 365 is steady.

• 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.
• To get the sync working you will either need to delete users or have the user limit on your account increased.
• If password writeback isn’t enabled or the service account doesn’t have the right permissions, new passwords won’t update in Active Directory.
• This blog talks about the causes behind Outlook synchronization errors and a few solutions to fix Outlook sync issues.
• That tells us if the new credentials made it to the cloud directory.
• If the old password still works, the reset probably hasn’t synced.
• We focus on restoring sync between Microsoft Entra ID (Azure AD), on-premises Active Directory, and user devices so everyone gets back in without headaches.
• Sync failure alerts do not always include a full summary or attachment, you can run a test sync to obtain this data.

Troubleshooting Microsoft 365 sync issues

This pops up a lot after admins reset a password in the Microsoft 365 admin center. That changes the password in Microsoft Entra ID, but not right away in your local Active Directory. You end up with mismatched passwords between the cloud and your local network. If you don't wish an inactive user to be made active by the M365 sync, you can add the user's email address to the sync forbid list. You can do this in the Microsoft 365 Sync Wizard on the configuration page of your platform settings. Knowing the reasons behind the Outlook sync issues will help us to fix this problem and prevent issues in communication and workflow.

Common Reasons Behind Outlook Sync Issues

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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.

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We show users how to reset passwords using approved methods like the Microsoft 365 portal or self-service password reset (SSPR). If someone changes their password only in the cloud or just on a local system, things can get out of sync pretty quickly. Bad settings in Azure AD Connect cause lots of password sync failures. If password writeback isn’t enabled or the service account doesn’t have the right permissions, new passwords won’t update in Active Directory. That leaves people locked out with their new password on the cloud but not locally. If users are facing syncing issues in Outlook due to corrupt Outlook data files, they must choose a professional tool, like Shoviv OST to PST Converter Tool.

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

We also scan Event Viewer logs under Applications and Services troubleshoot Outlook synchronizing folders error 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

On the sync server, we open the Synchronization Service Manager and check that the last sync finished without errors. Azure AD Connect handles password sync, but it runs on a schedule—usually every 30 minutes. So, if you just changed your password, there might be a short window where your old password still works and the new one hasn’t reached every system.

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Methods to fix Microsoft Outlook syncing error

Devices sometimes keep using cached passwords even after a successful sync. If users access multiple apps with the same login, we make sure Single Sign-On (SSO) settings line up so the new password works everywhere in Microsoft 365. We look at audit logs in the Microsoft 365 admin center to see when and where the password changed. That tells us if the new credentials made it to the cloud directory. We tell users to sign out completely and remove stored credentials from Windows Credential Manager or their device’s keychain.

Keeping Azure AD Connect up to flush DNS and re-sync Outlook date and testing sync regularly helps password resets flow like they’re supposed to. Password sync usually fails when credentials don’t update between Microsoft Entra ID (Azure AD) and your on-premises Active Directory. Most of the time, the problem comes from timing delays, configuration mistakes, or cached credentials on devices that don’t pick up new passwords. Outdated credentials get stuck on devices, password sync gets turned off, or Microsoft Entra Connect just doesn’t update like it should. Here’s a step-by-step approach to help you spot the issue, fix it, and avoid these sync delays down the road.