The sync will fail if the total number of all users (active or inactive) on your account exceeds the user limit placed upon it if present. The Summary sheet on connection status shows disconnected 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.

Methods to fix Microsoft Outlook syncing error

• The other solution to fix Outlook sync issues is recreating Microsoft Outlook profile.
• You can stop any accounts from being brought over by adding them to the sync deny list.
• The causes of sync issues and local failures in Outlook are explained in this guide, along with practical troubleshooting and resolution techniques.
• The sync will fail if the groups you selected to load users from no longer exist in Azure AD.
• Once you have completed the steps to fix Outlook sync errors, kindly check if the error has been fixed or not.
• 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.

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. I have multiple users experiencing sync errors with Outlook and office365. Another which is shown below, is a user opens a new message, or replies to one, and lets it sit for a while. When they go back to the message and press send they get an error that the message has been deleted. Ive repaired the OST and changed cache mode to only cache 1 year. The M365 sync establishes a synced dataset based on your M365 data and the filtering configuration of your sync.

Common Causes of Sync Issues in Outlook

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. There are various methods to resolve the Outlook sync issues, including manual and third-party solutions. Now, let us start with the manual processes to fix Outlook syncing errors.

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To solve your Outlook issues, download the application from the Microsoft website and follow the directions. After the files get repaired, restart the Outlook program to ensure that the Outlook syncing issues are resolved or not. The simplest way to resolve authentication issues is to rerun the authentication process by clicking the Sign in with Microsoft on Troubleshoot Office 365 Sync and Login Issues the Microsoft 365 settings page. You run the Microsoft consent process using an eligible M365 account after which you will be taken to the sync's setup wizard.

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

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. The Support and Recovery Assistant, a tool provided by Microsoft, can identify and resolve common Outlook problems. It is capable of automatically identifying problems with account setups, sync, and Fix Outlook Not Opening After Windows Update other typical mistakes.





Typically this is because the selected groups have been deleted from Azure AD since the M365 sync was configured on your account. After viewing, see fixing problems with directory synchronization for Microsoft 365 to correct any identified issues. 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. To get the sync working you will either need to delete users or have the user limit on your account increased. 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.



It is possible for a corrupted Outlook profile to impede synchronization. After these instructions, ensure the sync settings are correct and check everything is working well. This means that the authentication setup for your sync is no longer valid.



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 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.