How to Fix Cannot Access OST File in Outlook? – All Possible Solutions

Are you facing issues accessing OST files in Outlook?

Do not know — why it is happening?

Want to learn how to access these unapproachable OST files?

You are in right place…

We will provide a direct solution for the user query “cannot access OST files in Outlook application”. Keep reading to learn the practical solution. Before starting the solution process, first, let’s understand some real scenarios

User Query #1. Outlook 2016 Cannot Open OST File

User Query #2. Unable to Open Outlook OST File

User Query #3. Error in Opening OST File in Outlook

“I have 52 GB OST files on Outlook application. When I was trying to open the OST file in Outlook 2016, it couldn’t not open. Can anyone tell me why it is happening? And how can I access inaccessible OST files?
Thanks a ton.”

Why User Cannot Access OST Files in Outlook

Queries like these are frequently asked by users. Many reasons are responsible for this issue. Have a look at them.

Here is the solution you can rely on when you cannot access the OST file in the Outlook application.

Solution #1 Quit All Outlook Related Processes

  1. Choose “Task Manager” from the taskbar by right-clicking it, OR Press CTRL + ALT + Delete altogether, then select “Task Manager“.
  2. Go to the “Processes” tab.
  3. Look for something with the label “Communicator,” “Lync,” “ucmapi,” or “Outlook” in the title. Select any items that are connected to these, then select the “End task” icon.

Solution # 2: Restart The Computer to Fix Outlook OST Error

If after killing the Outlook process, the problem remains the same, then instead of going for any complicated process, simply choose the restart the system. Choose “Start” >> “Restart.”

Solution #3: Disable Cached Exchange Mode

  1. Quit Outlook program.
  2. Open Control Panel >> Mail option.
  3. Select “Email Accounts” from the drop-down menu.
  4. Now Select the “Email” tab.
  5. Select “Change” after selecting the email address that is prompting the alert (email.ost).
  6. Uncheck the box next to “Use Cached Exchanged Mode”.
  7. Click “Next” and then “Finish”.

Solution # 4: Fix Error Using the Outlook Import Export Wizard

If you have access to Outlook, you can use the Outlook Import/Export wizard to convert an OST file to a PST file.

Remember: – The Outlook Import/Export wizard cannot operate if the OST file is unavailable. Using the OST to PST converter tool in this situation is the best alternative to access the OST files.

Solution # 5: Search OST Files with SCANOST Utility

Recovering and Repairing OST Files in MS Outlook 2007/ 2010/ 2013. The SCANOST inbuilt tool in Microsoft Outlook 2007 can be used to restore Outlook OST files. To fix a corrupted OST file, a user simply needs to find the file on their local machine and run it on the device. After completion of the repair process, check if the OST files are not accessible now or not.

Note: – The Offline Storage table which has minor corruption issues can be fixed by it. But for major issues, you have to reach the professional solution that DataHelp OST to PST converter.

Now try to open Outlook once more. Hopefully, everything is functioning properly now.  Since this solution updates your Outlook settings to use the server directly, most probably your OST files inaccessibility issues will be resolved by now. You might face speed-related issues. If you’re having trouble with Cached Exchanged Mode disabled, try testing the “Use Cached Exchange Mode”.

What if OST files are corrupted?

If none of these solutions work, then chances are high that the OST file may be corrupted due to technical or logical issues. The next action you can perform is the repair and conversion of OST to PST format.

Later import those healthy files into the Outlook application. The next solution expresses complete guidelines for it.

Solution # 6: Create Healthy PST File from Damaged OST File

OST data integrity must be kept intact so that it can be accessible in Outlook. Trustworthy OST to PST wizard achieves this task sophisticated. To convert an OST file to a PST file, follow these simple steps.

Note: the below-mentioned steps will not fix the Outlook OST error. Instead of that, it will help you to create a healthy PST file from a corrupted OST file. After getting the healthy PST file, you can easily access it in any version of Microsoft Outlook.

Step 1: To begin, download the OST to PST Converter Wizard and launch on your Windows 10, 8, 7 versions. The home screen of the software will appear as shown below.

Step 2: Here you have two options to add your OST file into the software panel. Either Drag and drop OST files or browse them by clicking the Select Files button. According to my personal experience, you should go with the drag and drop option.

Step 3: Go to the system’s OST files and select them. Click the OK tab. Perform this step, if you had selected the select file option in the previous step.

Step 4: Select the Convert option. Before moving ahead carefully check the browsed OST file. If it is not correct then, first add the right OST file into the software panel and after that move to the next step. You can also add multiple OST files at a single time.

Step 5: Select a location to save the converted PST files. You can either select a system drive or any other externally connected storage drive. After complete the conversion process, the software will save the output file at the provided location. You can also apply the advance split option and create the required size PST file.

To continue, press the OK button.

The mission has been accomplished.

Your OST files will be converted to PST and saved in the position you choose in a matter of minutes.

Features of an OST to PST Converter

Know why you should use the DataHelp wizard to complete the conversion process. Understand the software capabilities:


Error saying “cannot access OST file in Outlook” is not less than a nightmare for Outlook users. We provided many manuals and also the direct solution to fix this issue.

If OST files are inaccessible due to corruption issues then you will need to convert them into healthy PST format and import them in Outlook.

Exporting OST files into the POP Outlook supported PST format is the perfect solution. Use professional software developed by DataHelp and Convert OST to PST format. So you should go with solution 6 to fix cannot access the OST file in Outlook error.

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