MS Outlook is no more an exclusively desktop-based email client as it enables synchronization with Microsoft Office 365. When Outlook is used as a component of Office 365, it becomes connected to Exchange Server. Outlook users often face different OST file errors during their Outlook usage, especially while connecting to Exchange. In this write-up, we will talk about topmost OST errors and their fixes. Thus, users will get a clear idea about OST errors and ways to resolve them. Let’s move straight to the OST file errors and their solutions.

Top 5 OST Errors and Their Fixing Method

We have chosen top 5 OST errors that occur frequently to Outlook users. Now we will know about the errors in brief and its solutions.

OST Error #1: “Cannot open your default email folders.” Error
This error message appears when the particular OST file is damaged and as a result, Outlook is unable to recognize this file. It may also occur if Exchange fails to connect to the mailbox that is associated with that particular OST file.

Solution: To resolve this problem, users can take help of OST Recovery Tool. This application has the ability to resolve all types of OST file corruption, regardless of OST file size. The program both repairs and converts OST to PST and relieves you from “Cannot Open Default Email Folder” error.

OST Error #2: “Unable to Expand the Folder” Error
This error message appears when users add another mailbox to their Outlook and try to open the shared folder.

Solution: You have to set “Folder Visible” option for the latter mailbox you have added.
You have to perform this on a system that contains the mailbox and the folder you want to share. Open Outlook and right-click on the mailbox and select Properties from the shortcut menu.

Click on Permission tab and check Folder visible option. Click OK.

OST Error #3: “Encounter a Large Numbers of Conflict Items” Error

This error message is generated in case of corrupt or damaged OST files.

Solution: Users can repair OST file using built-in utilities named Scanost.exe and scanpst.exe. While scanost.exe repairs OST file in older Outlook versions, Inbox Repair Tool (scanpst.exe) can be used to repair OST file in all latest Outlook versions like Outlook 2016, 2013, 2010, and 2007. If the tools fail to repair OST file, try the following steps:

  1. Close Outlook and go to Windows Explorer to click on Start>> Control Panel.
  2. Make sure “Classic View” mode is enabled in Control Panel and click on Mail.
  3. Go to Mail Setup dialog box and then click on Show Profiles.
  4. Find out the defective profile and terminate it.
  5. Once you have removed all damaged profiles, click Add to create a new profile. Add a new email account according to server settings.
  6. Open MS Outlook and connect it to the server to synchronize.
    OST Error #4: “Cannot Open Particular Outlook Items when Offline” Error

    This error is often encountered by Outlook users as the number of Outlook items does not match with the number of items stored in Server.

    Solution: Remove filters for Outlook folders by implementing these steps.

    1. Navigate to Outlook details pane and right-click on the folder you are having problems with. Select Properties from the options. 
    2. Select Synchronization tab>> click Filter
    3. Now click on Clear All option or change filter criteria as per your requirement.

    OST Error #5: OST Errors that Occur during Exchange Server Synchronization

    When users try to synchronize OST file with MS Exchange Server, they face a number of errors. To avoid those errors, they may follow the following techniques.

    Solution A: Turn On Outlook Cached Mode

    In case you have turned off cached mode in Outlook, enable it to solve the problem. Launch Outlook and click on Tools >> Account Settings.


    2. Click on Data Files tab. Choose the profile name you wish to synchronize and click on Set As Default. 

    3. Click on Settings. Go to Advanced tab and enable the option named “Use Cached Exchange Mode.” 
    Solution B: Manually Synchronize OST File to Exchange Server

    1. First of all, you need to select the folder you want to sync with Exchange. 

    2. Open Outlook and click on Tools >> Send/Receive >> This Folder (the folder you want to sync.)

    Solution C: Enable Auto Sync Option for OST File 

    Enable automatic synchronization of all Outlook folders. 
    1. Open Outlook and click on Tools. Now, choose Options.
    2. Click on Mail Setup tab and check the box beside “Send immediately when connected.”

    Wrapping Up 

    As many people complain about OST file errors and demand for their solutions, this post discussed topmost OST errors and their fixes. Users can take help of the remedial methods described here to solve any Outlook OST error occurring to them. All techniques have been described in a lucid manner so that users easily understand the instructions.
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    Diptesh Kumar Bhakat is proud to be the author of fastest growing tech blogs. He is a tech-savvy, SEO Expert, SMO Expert, SMM Specialist and a professional Blogger. Except blogging, he is so much found in photography, superbike riding. He has a very close attachment to the tech world and loves to blog on his fav topics. He has also contributed to many regional dailies and authored guest posts on some of the leading tech blogs. Professionally, he is a tech blogger and reviewer. he is a very energetic person who constantly puts up an evil smile to counter any obstacle in his manner. This dude is highly unpredictable and in reality, you can’t recognize what’s coming from him…be it his articles, generating an aura, or his personality. Mr. Diptesh is completed his B.Tech in Mechanical Engineering, as everybody thinks about one question that how a mechanical engineer can make a website?? Is it strange!!!!!!!! Yes it is. But there is a big story we will update soon.


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