This means that the authentication setup for your sync is no longer valid.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. To update from Azure AD Sync to Microsoft Entra Connect, see the upgrade instructions.

Top questions it leaders have about microsoft copilot (and how to answer them)

• The sync will fail if the groups you selected to load users from no longer exist in Azure AD.
• TrustedTech is dedicated to being a reliable resource for all software and technology support needs.
• To diagnose and automatically fix several common Microsoft 365 sign-in issues, run the Microsoft 365 Sign-in troubleshooter.
• Sync failure alerts do not always include a full summary or attachment, you can run a test sync to obtain this data.
• From sync errors to sign-in challenges and collaboration setbacks, these common Office 365 troubleshooting techniques can restore service quickly.
• These figures will give you an impression of how far over the limit the account is.

I have multiple mailbox not updating on IMAP 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.

I got an error message that my company has exceeded the number of objects that can be synchronized

The idea is to provide a recycle bin of users who you can delete when repair corrupted OST in Outlook you no longer need them. You can view your inactive users on the Users page and delete them as you see fit. 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. 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.

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

Comprehensive repair solutions for online Outlook email repair utility Office apps—both Quick Repair and Online Repair to ensure minimal downtime. To identify Microsoft-side issues affecting Office 365 services. Are you facing Microsoft Office 365 not opening or continuing to crash? This is one of the most frustrating issues with Microsoft Office, often caused by update failures, corrupted files, or compatibility problems. Discover how IT leaders can address key Microsoft Copilot questions on cost, deployment, security, and integration to maximize ROI and adoption. In these cases, direct escalation to Microsoft or working with a Microsoft CSP partner, such as TrustedTech, can expedite resolution and minimize downtime.

Tools & Methods To Use to Troubleshoot Office 365 Issues

While M365 is highly stable, it’s not immune to occasional disruptions. 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 AD since the M365 sync was configured on your account. To get the sync working you will either need to delete users or have the user limit on your account increased.