This means that the authentication setup for your sync is no longer valid.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.
• Find out what to do if you are having issues with syncing users or groups from Microsoft 365.
• To diagnose and automatically fix several common Microsoft 365 sign-in issues, run the Microsoft 365 Sign-in troubleshooter.
• 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.
• 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 fix MFA prompts not working 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

To diagnose Outlook and OneDrive connection issues that often cause Office 365 not working problems. Create your account and connect with a Fix Outlook Not Opening After Windows Update world of communities. I have a user who is having trouble syncing with Microsoft 365. The authentication issue occurs because of missing package information about either the Active Directory Authentication Library (ADAL) or Live ID.

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

Comprehensive repair solutions for Fix Outlook and Office 365 Errors 2025 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

The most common reason for missing users is that you've run a Test Sync, instead of a Manual Sync. You can run a Manual Sync from the Microsoft 365 Sync page. If that doesn't resolve your missing users issue, please follow our guide to troubleshooting missing users below. Whether you’re struggling with Microsoft 365 sign-in problems, Office 365 not working, or syncing issues, our team is here to help. Don’t let technical problems affect your productivity—contact us for immediate assistance.