How to Fix: OST File Cannot Be Opened in Outlook

Microsoft Outlook is one of the most important applications for professional communication but it is not always protected from technical errors. One of the most frustrating errors a user can face is that your OST file cannot be opened.

This happens when the Offline Storage Table (OST) file which is the local copy of your mailbox becomes corrupted or incorrectly connected with the Exchange Server.

When you cannot open OST file in Outlook it can pause your productivity and you can lose access to your emails, calendar invites and contact lists.

Today we will look at everything you need to know about OST files and provide a step-by-step process to fix access issues whether you are a home user or an IT admin. We will look at the manual and professional methods like the SysTools OST to PST Converter Tool that helps to convert the OST files to PST format.

What is an OST File?

An OST file is a Microsoft Outlook data file that creates a local copy of your mailbox. When you use Outlook it downloads a copy of your data from the server and saves it on your computer. This allows you to read emails even when you are not connected to the internet.

This file is prone to connection issues as it is regularly being updated. You will find that your OST file cannot be accessed if the connection between your computer and the server is disturbed or if Outlook closes improperly.

Why Your OST File Cannot Be Opened?

There are many reasons why you may see cannot open OST file in Outlook. Let us take a look at some of these reasons:

1. Improper shutdown: Turning off your computer while Outlook is still working.
2. Large File Size: OST files have a size limit, so when they are too big they can be unstable.
3. Incompatible Add-ins: Sometimes third-party tools can damage the file.
4. Connection Issues: A connection issue between the server and the local file.

Method 1: End Outlook Processes in Task Manager

Many times the reason an OST file cannot be opened is that Outlook is still running in the background. In such cases Outlook locks the file and prevents a new session from starting. Follow the steps mentioned below if you are stuck in such a situation:

1. Press Ctrl + Shift + Esc to open the Task Manager.
2. Look for Microsoft Outlook under the Processes tab.
3. Right-click it and select End Task.
4. Restart Microsoft Outlook and see if the OST file cannot be accessed in Outlook error is still there.

Method 2: Disable Outlook Add-ins

Another reason the OST file cannot be accessed is faulty add-ins. If you want to test this you can run Microsoft Outlook in Safe Mode. Use the following steps to solve this problem:

1. Press Windows Key + R to open the Run dialog.
2. Type outlook.exe and hit Enter.
3. An add-in is the problem if Outlook opens normally.
4. Go to File > Options > Add-ins and at the bottom select COM Add-ins and click Go.
5. Uncheck all add-ins and restart Microsoft Outlook to enable them one by one to find the reason.

If you want to know how to import OST to the New and Classic Outlook, you can find it here.

Method 3: The Professional Solution

The manual methods fail when the OST file cannot be opened due to severe corruption or if the account is no longer connected to the server. In such cases using a professional tool allows you to save data.

Why Use This Tool:

1. Dual scanning modes: The Quick Scan option is available for small errors that can be fixed quickly. The Advanced Scan option reconstructs the file structure to recover emails and attachments.
2. Recover Orphaned Files: This tool works independently, meaning that it can extract data even if the server is down, the account is deleted or the OST file cannot be accessed because the original profile does not exist.
3. Preview Before Conversion: Provides a 7+ mode preview including the Hex, Header, and MIME views. This allows you to verify that your data is recoverable even while the original OST file cannot be opened in Outlook
4. Maintains Data Integrity: Ensures that the hierarchy remains as it was before the OST file could not be accessed and this makes the transition to the new file easy.

Look at the following steps if you want to use this tool:

1. Download and start the software.
2. Click on Add File to load the file when your OST file cannot be accessed.
3. The software will scan the file and provide a preview of all emails, contacts and calendars.
4. Select PST as the export format and then click Export.
5. You can now import the new PST file into Outlook when it is converted. This provides a new and healthy data source by solving the issue where the OST file cannot be accessed in Outlook.



Read: EML Files Not Opening in Outlook? Causes, Fixes &

Method 4: Recreating the OST File

You can delete the OST file since it is just a copy of what is on the server. Outlook will create a brand new, healthy file the next time you open it. This is the most effective method when an OST file cannot be opened in Outlook.

1. Close Microsoft Outlook.
2. Open the Run dialog, type %localappdata%\Microsoft\Outlook and press Enter.
3. Locate the OST file connected with your email address.
4. Right-click the file and select Delete.
5. Open Microsoft Outlook. This will permanently fix the cannot open OST file in Outlook error.

Method 5: Using the Inbox Repair Tool

The built-in repair tool is designed for PST files but it can sometimes fix minor header issues when an OST file cannot be accessed. Use these steps to solve the problems:

1. Locate your Outlook installation folder.
2. Find and run SCANPST.EXE.
3. Select your OST file.
4. Click Start and then click Repair if errors are found.

Conclusion

It can be frustrating to see that your OST file cannot be opened since it is the mirrored image of your server mailbox. Keeping your Outlook updated and performing regular cleanups of your mailbox to keep the file manageable will ensure that you never have to worry about your OST file not opening in Outlook.

You change your frozen screen to a fully functioning inbox by following the steps mentioned above.