Learn how to resolve OST file synchronization issues

Barclay Tcareva
Barclay Tcareva

Updated On - June 19, 2024

Summary: The discrepancy between offline & online mailbox contents signifies the synchronization issue of the OST file with the Exchange Server. It hampers the performance of the user while working with Outlook. So, the blog will help you to identify the reasons behind the issue & provide practical approaches to resolve it. Additionally, you can explore an advanced professional tool like Recoveryfix for OST to PST as an instant solution for all OST concerns.

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Offline Storage Table (OST) files are the replica of the Exchange Server mailbox that stores on your local system when you enable the Cached Exchange Mode in Outlook. It allows the users to work even with an unstable internet connection & whatever change you make will sync automatically once the connection is restored. It means whatever operation you will perform either offline or online, Outlook synchronizes it to the Exchange Server when connectivity is there.

But sometimes, due to some technical glitches, offline OST file experience synchronization issue with the Exchange Server. As it limits the storing of mailbox content further, it will impact the user’s productivity. Also, in the worst scenarios like Exchange Server crashes or OST file corruption, accessing the mailbox content becomes challenging for the user.

There are various symptoms that help you to check whether your OST file has synchronization issue like some mailbox items missing from your OST file, or frequently receiving error messages from Outlook. But before moving further, it is important to validate whether you have a synchronization issue or not.

How would you know that your OST file is not synchronized?

It will help you to determine whether your offline folders are being synchronized or not. So, follow the given steps to execute the process:

  1. Open the Outlook application, right-click on the folders & go to the Properties.Open the Outlook application
  2. Now, go to the Synchronization option & in the Statics for this folder section, and verify the settings like how many items server folders contain or how many offline folders contain.Statics for this folder
  3. If the number is the same, then it will signify that your synchronization is working properly & vice versa will reflect synchronization issues in the OST file.
Causes for the synchronization issue

To identify a suitable approach for resolving the issue, you need to understand the causes behind this issue. There may be several reasons that might be responsible for the error, but the major ones that increase the chances of getting synchronization issues are mentioned below:

  • Bad hardware sectors
  • Oversized OST file
  • Failure of Exchange Server or database.
  • Incompatible Outlook add-ins.
  • Low internet connection
  • Corrupt or damaged Outlook data file.
Quick ways to resolve the synchronization issue

Upon analyzing the causes behind the issue and after several hits & trials, we have come up with three practical methods that help you get relief from the issue:

Solution 1: Resynchronize folders using Update Folders option in Outlook

Once you resynchronize your folders, it will sync your folders once again with the Exchange Server, which might be helpful to resolve the issue. So, here are the steps:

  1. Open the Outlook application, right-click on the folder & choose the Properties option from the drop-down.
  2. In the General section of the next window, click on the Clear Offline Items followed by the OK option.Clear Offline Items
  3. Now, go to the Send/Receive tab of the Outlook window & then click on the Update Folders option.Update Folders
  4. Solution 2: Recreate the OST file

    Recreating the OST file also helps you to resolve the issue. It can be done by deleting the OST file that is facing a synchronization issue. After this, Outlook will create the new OST file & start synchronizing the mailbox items with it. Performing this method should fix the Outlook sync issues. Now, you can locate your OST file by following the given steps:

    1. Launch the Outlook application & go to the File> Account Settings >Account Settings option.Launch the Outlook application
    2. In the Data Files section select the profile & click on the Open File Location option to locate the OST file location.Open File Location
    3. Solution 3: Using Inbox Repair Tool (ScanOST.exe/ScanPST.exe)

      It is one of the best Outlook’s built-in utilities that scan the files & if an error is found, it will repair or fix it. It mainly handles issues related to synchronization or maintaining the structure of the file.

      Let’s delve into the steps to utilize this utility:

      Note: For Outlook 2007 or below versions, ScanOST.exe is used to scan or repair OST files, whereas Outlook 2010 or later versions use ScanPST.exe to scan or repair both OST and PST files.

      1. Close the Outlook application & navigate to the given location to open the tool:

        Outlook 2019: C:\Program Files (x86)\Microsoft Office\root\Office16

        Outlook 2016: C:\Program Files (x86)\Microsoft Office\root\Office16

        Outlook 2013: C:\Program Files (x86)\Microsoft Office\Office15

      2. Open the ScanPST.exe/ScanOST.exe tool, browse the file that you want to repair & click on the Start option to begin scan.browse the file that you want to repair
      3. It will scan the file & display the errors, then click on the Repair option to fix it. Finally, restart Outlook & check whether the issue is resolved or not.click on the Repair option to fix it

      Note: It will also allow you the option to make a backup of scanned files before repairing them, which will help you to be on the safer side.

      Why choosing an advanced tool is beneficial?

      Although manual methods help you to resolve the synchronization issues of the OST files with the Exchange Server, if your file is severely corrupted or damaged or your Outlook profile is missing, then these methods may not be supportive of tackling it. Also, performing these methods needs utmost attention, which makes the process time-consuming & complex. Thus, to avoid such circumstances, using third-party tools is always considerable.

      Recoveryfix for OST to PST is one such designed OST recovery software, which exercises an advanced algorithm to repair damaged files and facilitates multiple saving options for the user’s feasibility. Apart from these features, the software has been compiled with several other elite features that eliminate the risk of data loss due to synchronization issues and retrieve OST files in their original format.


      The blog has discussed the causes of the OST file synchronization issue & provided corresponding practical methods to fix it. By following the mentioned methods, you can synchronize your offline mailbox folders with the Exchange Server until your OST files are in a good state or you have your Outlook profile. Therefore, utilizing the recommended tool is beneficial to handle all OST-associated issues, even in the worst scenarios.

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