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on January 12, 2026
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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. For the soft match to work, the object to be soft-matched with shouldn't have any value for the immutableId attribute.
Fix the InvalidHardMatch error
When Microsoft Entra ID attempts to soft match two objects, it's possible that two objects of different "object type," like user, group, or contact, have the same values for the attributes used to perform the soft match. Because duplication of these attributes isn't permitted in Microsoft Entra ID, the operation can result in an ObjectTypeMismatch sync error. There are various methods to resolve the Outlook sync issues, including manual and third-party solutions. Firstly, we will discuss a few manual methods to resolve this Outlook error and share the stepwise procedure of each method to successfully fix synchronization issues. Now, let us start with the manual processes to fix Outlook syncing errors.
If you need to clear an InvalidHardMatch error and match the account successfully, you can enable hard match again as described in Hard-match vs Soft-match. After performing these steps, Outlook’s all folders will be synced to the server. If this method doesn’t troubleshoot Outlook synchronizing folders error work for you, navigate to other solutions. The Users Loaded count will be 0 if all users fail to meet the system's requirements for user records.
Fix the Existing Admin Role Conflict error
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. You can do this in the Microsoft 365 Sync Wizard on the configuration page of your platform FixTechGuide Windows update Outlook fix settings. Review the user properties and remove attribute values that might no longer be required.
Mailing Address
Knowing the reasons behind the Outlook sync FixTechGuide login issue guide issues will help us to fix this problem and prevent issues in communication and workflow. 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. Find out what to do if you are having issues with syncing users or groups from Microsoft 365. The Microsoft Entra Connect client is failing to delete users during migration from hybrid to cloud only, resulting in Error Type 114. Microsoft Entra ID enforces various restrictions on the data itself before allowing that data to be written into the directory. These restrictions are to ensure that end users get the best possible experience while using the applications that depend on this data.
What should I do if my sync failed due to authentication issues?
The system requires that users have a first name, last name and a valid email address that conforms with your domain lock if enabled. To get the sync working you will either need to delete users or have the user limit on your account increased. The most common reason for missing users is that you've run a Test Sync, instead of a Manual Sync.
Outlook sync issues can be because of corrupted Outlook OST or PST files.Users can also try its free demo version in their system and process the first 50 items from each folder freely.For the soft match to work, the object to be soft-matched with shouldn't have any value for the immutableId attribute.The admin adds a new user or contact in on-premises Active Directory that isn't synced to Microsoft Entra ID yet with the same value for the proxyAddresses attribute as that of the Microsoft 365 group.Now, we will verify the server settings to fix the Outlook synchronization error.Incorrect Outlook settings can also be one of the reasons behind Outlook synchronization errors.If you need to clear an InvalidHardMatch error and match the account successfully, you can enable hard match again as described in Hard-match vs Soft-match.
For more information, see Microsoft Entra userPrincipalName population. Users can also convert OST files into various file formats, including PST, HTML, EML, MSG, vCard, etc. It also provides the option to export the Outlook OST file into Office 365 and Live Exchange mailboxes. This software also has a splitter option to split large-sized PST files into smaller ones, helping users prevent oversized PST file issues. After the files get repaired, restart the Outlook program to ensure that the Outlook syncing issues are resolved or not.
If users are facing syncing issues in Outlook due to corrupt Outlook data files, they must choose a professional tool, like Shoviv OST to PST Converter Tool. This software allows users to process numerous OST files at once without any size limitations. Moreover, it maintains the folder hierarchy and metaproperties of the data when processing Outlook data files.
Method 4: Recreating the Outlook Profile
You can stop any accounts from being brought over by adding them to the sync deny list. 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. This section discusses LargeObject or ExceededAllowedLength errors.