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Microsoft Outlook has become email users’ favorite personal data managing application due to the variety of services and facilities it offers. To manage its data well, it stores all the user’s mailbox data for offline work; it saves data in an OST file -Offline Storage Folder.

Any changes in the mailbox that the user makes are saved offline in OST files and then updated in the mailbox server by synchronization. This synchronization between OST files and the mailbox is responsible for maintaining a smooth and uninterrupted email communication system. Often some emails get stuck in Outlook and users face gaps in the messages. When users observe discrepancies, they should understand that their Outlook mailbox is experiencing synchronization issues. This must be resolved immediately. If you face this error, you have landed at the right place because, in this article, we will discuss the Outlook Synchronization Log issue and the methods to fix it quickly.

How do we identify this problem?

When users face any of these situations, it is clearly indicating that their Microsoft Outlook app or Web app is not synchronizing the data as it should-

  • Indicator 1: The issue is not reflected when the Cached Mode is disabled.
  • Indicator 2: Variations in the messages of MS Outlook and Web app.
  • Indicator 3: Some contents are missing from the OST file or mailbox even after a complete synchronization process.
  • Indicator 4: Receiving some error messages in Outlook.
Factors responsible for sync issues

These are the reasons which are behind this problem and do make sure to avoid them in the future-

  • A severely damaged or corrupted OST file.
  • Poor internet connectivity.
  • Trying to access from mobile devices.
  • Server failure issues.
More about Outlook synchronization issues?

Due to synchronization issues, all the log files are saved in a separate folder called Sync Issues in Outlook. Further, this is divided depending upon the exact issue.

This folder acts as a container for all the synchronization logs which are created. All this data is stored locally and cannot be viewed on a different device or web application. This Sync Issue folder is further categorized into 3 separate sub-folders:

  • Conflicts- This folder is responsible for storing all the data that has multiple copies or conflicting with the original one.
  • Local Failures- This contains all the items which could not be synchronized or sent to the mailbox server from the local file.
  • Server Failures- As the name suggests, all the items which failed during the synchronization process appear in this folder.
How to check the synchronization settings in Outlook?

When there is a need to check if any sync issue exists between the Exchange Server and OST file, follow the simple steps-

  1. Launch MS Outlook, right-click on any folder, and select Properties
  2. The Drafts Properties window will open and carefully check the Last Synchronized data.
Methods to fix Outlook Synchronization Log issue

Before you proceed with the solutions, do a re-check for the following factors as well-

  • Ensure an uninterrupted internet connection.
  • Verify all the server and Outlook settings.
  • Check if the Outlook profile is active.
  • Verify the availability of the server.
Method A: Switch off the Cached Exchange Mode

The Cached Exchange Mode saves a copy of the user’s mailbox on the computer and updates the same on the server. By turning it off, the sync folder will also be disabled. This is done to check whether the Cache Mode is responsible or if there lies a bigger problem.

  1. Launch Outlook and click on on File
  2. Select Account Settings > Account Settings.Account Settings
  3. Select your profile and click on Change.Click on Change
  4. Uncheck the box against Cached Exchange Mode. Now, close and restart the Outlook application.
Method B: Create a new Outlook profile

These steps will help you to create a new profile for MS Outlook-

  1. Open Control Panel and select the Mail option.
  2. Now, click on Show Profiles in the Profiles section.Show Profiles
  3. Select the Add option.
    Add option
  4. Configure your Exchange account and settings. Enter all the details. Click on Next and then on, Finish.Click on Next and then finish
Method C: Empty all the Sync Issues Data

Now, since synchronization is not working, you can opt to empty the entire Sync Issues folder. This will allow users to have a chance to start again; This might resolve the existing issue.

  1. In Outlook, click on the 3 dots present on the bottom left and click on on Folders
  2. The Sync Issues folder will appear on the left panel. Click on it.
    Sync Issues folder and Click on it
  3. Now, select all the messages and empty the folder. Exit Outlook.
Method D: Repair the corrupted OST file

If none of the above methods work, it is clear that the corrupted OST files are behind this Synchronization Log issue. It is important to repair the OST file and save all the data before the situation gets worse.

To perform this repair, you will have to rename the OST file, create a new file, and then synchronize that one with the server. This will solve the sync log issue but will open doors to more problems. There is a good chance of losing all the data from the older OST file, which has gone corrupt.

A better solution is to try a professional utility- Kernel for OST to PST. This software has been curated with powerful algorithms that work to retrieve all items, including emails, contacts, tasks, notes, attachments, calendars, etc., of an inaccessible, corrupt, or orphaned OST file. The process is simple, and beginners can perform without any additional guidance. Since it’s a professional tool, the accuracy and security of data are always on point.



The OST file and mailbox server synchronize with each other to ensure smooth offline working. However, if users start observing some discrepancies or error messages, it is a consequence of a Synchronization Log issue. This can create a huge gap in the communication between users and their work. It becomes crucial to resolving this. Check the settings, switch off Cached Exchange Mode, empty the Sync Issues folder, and create a new profile. A highly corrupted OST file is also responsible for such a ruckus. This can be resolved by following some free methods to covert OST to PST but those do not guarantee a successful conversion. For a simple and effective conversion, a professional software has been recommended.

Kernel for OST to PST