To resolve these issues you should run the steps in this article and check whether the groups in your sync's filtering preference contain users in Azure AD. The sync will fail if the groups you Outlook OST vs PST repair 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. For details see Identify directory synchronization errors in Microsoft 365. Users can also convert OST files into various file formats, including PST, HTML, EML, MSG, vCard, etc.

I need technical support with my 365 acct as I have a personal 365 acct and I also need to use a work Outlook Exchange

The error message in the Summary sheet of the Sync Summary spreadsheet attachment can also highlight the reason for this. You will need to have the correct privileges set on your Azure account in order to set up the M365 sync. In these cases, direct escalation to Microsoft or working with a Microsoft CSP partner, such as TrustedTech, can expedite resolution and minimize downtime.

Built-in M365 Troubleshooting Tools

• Ive repaired the OST and changed cache mode to only cache 1 year.
• The system requires that users have a first name, last name and a valid email address that conforms with your domain lock if enabled.
• Before we know the solutions, we will understand a few common causes of the Outlook sync problem.
• You should run a test sync after re-authenticating the sync to ensure it is working.
• The sync does not delete users but rather sets them to inactive.
• Microsoft 365 is a robust platform, but when problems arise, fast resolution is key to productivity.

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 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. I have multiple users experiencing sync errors with Outlook and office365.

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