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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.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

Similarly you should review the Users Deactivated sheet on the sync summary spreadsheet attachment as you can also delete these users to bring your total down. You'll also receive a mail (to the alternate email and to your admin email) from Microsoft 365 that indicates your tenant has encountered directory synchronization errors. For details see Identify directory synchronization errors in Microsoft 365. We also check the synchronization scheduler to confirm delta and full sync cycles finish successfully. We check that Microsoft Entra Connect (Azure AD Connect) runs the latest version and password sync is on.

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 Online Outlook Email Repair Utility 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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Our training has quick guides about what happens after you update your password. For example, you might get signed out or have to reauthenticate on your phone. We also remind users to refresh their Office sign-in token by signing out of all Microsoft apps and signing back in with the new password.

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The Summary sheet on the spreadsheet attachment of your sync summary includes an Updated User Count and User Limit. These figures will give you an impression of how far over the limit the account is. Sync failure alerts do not always include a full summary or attachment, you can run a test sync to obtain this data. 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 identify potential issues and fix them.

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

We also scan Event Viewer logs under Applications and Services disable faulty add-ins in Outlook 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.

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. You will need to have the correct privileges set on your Azure account in order to set up the M365 sync.

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Methods to fix Microsoft Outlook syncing error

Before finding solutions, we suggest that users check their internet connection. Sometimes, Outlook sync issues can arise because of poor internet connection. If you are still facing this issue, kindly follow the solutions below to fix the sync issues in Outlook.

Keeping Azure AD Connect up to connection status shows disconnected 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.