How to Fix OST File Cannot Be Opened Outlook Issue Easily

Mark Regan
Published: March 12th, 2026 • 11 Min Read

Facing OST file cannot be opened Outlook issue is a noticeable problem for every user. It’s become more problematic when a user is a business professional and urgently needs to send an important email to another business owner. In such cases, it’s become hard to resolve the issue of OST files not opening in Outlook.

In this blog post, we explain the core reasons that tells, why users encounter the “Outlook OST file cannot be accessed” error. Along with that, we are providing you with both manual and automatic solutions to fix your “Outlook not able to open OST file” issue. Read this blog post till the end to find and solve the unable to open OST file in Outlook issue.

Let’s get started with understanding the core reasons for the Outlook OST file not opening in the next section.

Possible Reasons OST File Cannot Be Opened Outlook

Accidental Actions: When a hard drive gets damaged, or sudden power cuts occur, the OST files may become corrupted, and make users unable to open OST file in Outlook.
Server Connectivity: Sometimes, Microsoft Outlook fails to connect an OST file with the Exchange Server, making the file inaccessible, and you get an error message of OST file not opening in Outlook
Unsupported Add-ins: When users unknowingly install add-ins that are not compatible with their Outlook version, then OST files may become inaccessible.
Outlook Older Version: Older versions have compatibility issues that affect OST files, making them inaccessible. You will see the “Outlook OST file could not be opened” message.
Corrupt Profile: When your account gets corrupted or misconfigured with Microsoft Outlook, then Outlook is unable to load data from OST file, and shows the failure message on your screen.
Software Interruptions: Sometimes, third-party software and antivirus programs are running in the background, which stop accessing Outlook to open OST files. Due to which Outlook not able to open OST file.

So, these are the core reasons that inform why Microsoft Outlook cannot open OST files on it.

After knowing these causes, let’s move ahead to use solutions to fix “OST file cannot be opened Outlook” issue in the next section.

Manual Ways to Fix Outlook OST File Cannot Be Accessed Issue

You can fix your Outlook OST file not opening issues by using the top eight tested solutions listed below.

First Solution: Close and Restart

1^s^tStep: Close Outlook Properly

Go to the “File” menu and click on “Exit” button to close Outlook or close normally with “X”.
After that, open “Task Manager” application, press “Ctrl + Shift + Esc” shortcut keys.
Then, find “Microsoft Outlook” in the list of “applications” and select Outlook.
Finally, click on “End Task” button to close Outlook properly.

2^nd Step: Reopen Outlook

Open Microsoft Outlook normally on your desktop PC.
Then, check that your Outlook application is syncing successfully.
After a successful sync with the server, your error “unable to open OST file in Outlook” has been resolved.

Second Solution: Add a new profile

1^s^tStep: Remove Existing Profile

Open Control Panel on your computer PC.
Now, search for “Mail” option and click on it.
Click on “Show Profiles” in the “Mail Setup” window.
After that, select the associated profile and click “Remove” button to remove profile.

2^nd Step: Create a New Profile

After removal of the existing Profile from “Mail Setup” window.
Now, click on “Show Profiles” and hit the “Add” button.
Then, enter a name for the new email profile and click “OK” button.
Now, follow all the given on-screen instructions to set up your new profile.
Done! After this solution, your OST file cannot be opened Outlook issue is solved, and you will open a new OST file for your new account.

Third Solution: Open Outlook in Safe Mode

Open start menu on your Windows PC and search for Run, or press the Windows key + R to open the Run dialog.
After that, type outlook.exe /safe and click “OK.”
Now wait to sync the Outlook with the email server and fetch all your emails.
Done! Your Outlook will start in Safe Mode, and after closing Safe Mode, the OST file not opening in Outlook issue will be solved.

Fourth Solution: Disabling and Enabling Add-ins

To use this solution, you need to open Outlook in Safe Mode. The opening method is given in the above solution

1^s^tStep: Disable Add-ins from Outlook options

Click on “File” from top menu and choose “Options.”
Go to the “Add-ins” tab, click on “COM Add-ins”, and hit the “Go” button.
Now, “uncheck” the box of unnecessary add-ins that cause the issue, and click on “OK” button.
After that, close and reopen Outlook to check the error.

2^nd Step: Enable Add-ins

Follow the same given first two instructions in the first step to open the Add-ins menu in your Outlook.

Check the boxes of add-ins one by one that you had previously disabled.
Then, click on “OK” button and close the Outlook application.
After a few minutes, restart your Outlook normally.
Done! Your OST file becomes accessible.

Fifth Solution: Update Application and Windows

1^s^tStep: Update Outlook

Open Microsoft Outlook on your Windows PC.
Go to the “File” menu and click on “Office Account” option.
After that, click on the “Update Options” and hit “Update Now” button.
Done! Now wait for some time to get your Outlook up to date.

2^nd Step: Update Windows

Open your Windows settings on your computer.
Select and open “Windows Update” option.
Finally, click on “Check for Update” button and install all the latest updates on your computer.
Done! After updating, your Outlook starts working normally, and your OST file becomes accessible.

Sixth Solution: Inbox Repair

Open This PC on your computer PC.
Then, search this location on your This PC window.
“C:\Program Files\Microsoft Office\root\OfficeXX\”
Open ScanPST.exe.
After that, click “Browse” button and select “OST” file from the location given below.
“C:\Users\user\AppData\Local\Microsoft\Outlook.”
Then, click on “Start” button to start the “Repair.”
Now, restart Outlook and click “Send/Receive” to check it’s working.
Done! Your Outlook OST file cannot be accessed issue is resolved.

Seventh Solution: Reconfigure Account

Open Microsoft Outlook on your laptop PC.
Go to the “File,” click on the “account settings” and choose “account settings.”
Select the configured account, click “Remove” button, and select “Yes” option.
Then, restart your Outlook application.
After that, click on “File” and hit “add account” button.
Now, enter your email ID and password, and press the connect button.
Done! After the reconfiguration of your account, your OST file is accessible.

Eighth Solution: Turn off Cached

1^s^tStep: Account Settings Panel

Open Outlook on your Laptop computer.
Click on “File” from navigation bar and click “Account Settings.”
Then, hit the “Account Settings” to open the Email Accounts Panel.

2^nd Step: Open Exchange Mode

After first step, select the “email account” and click on “Change” button.
Then, click on “More Settings” and switch to “Advanced” tab.
After that, check mark on “Use Cached Exchange Mode” and “download shared folders” options.
Click “OK” to complete the settings.
Finally, close and reopen Outlook and check your OST file is starts working normally.

These are the tested manual solutions that will help you to fix your OST file cannot be opened Outlook issue. All the given manual solutions have some drawbacks that you need to be aware of.

Drawbacks of Manual Solutions

Restarting Microsoft Outlook is only effective when your Outlook is suffering from temporary glitches or minor sync issues.
Removal of the existing account leads to loss of custom rules, configurations, and signatures from Outlook, and the reconfiguration process is time-consuming.
Adding a new profile in Outlook is useful when you need to open your Outlook application for urgent cases. This solution does not fix your existing OST file issue.
Opening Outlook in Safe Mode might be helpful because sometimes Outlook does not open easily in Safe Mode.
All manual solutions have multiple steps, which are not easy for non-tech users, and using all the steps incorrectly can lead to the risk of account corruption.
Disabling and enabling the Add-ins solution only works when your Outlook has an issue with specific add-ins. If your OST file is corrupted, then this solution doesn’t work.
Updating Outlook and Windows might be helpful for temporary and minor OST-related errors, but this solution does not fix the OST error completely.
Turning off/on cached exchange mode does not work effectively in every environment. If your network is slow or you have a server issue, then this might impact negative impact on performance and emails.
The use of ScanPST.exe tool fixes minor corruption of OST file. If your OST file size is more than the tool capacity, then this tool does not work effectively.

These were the drawbacks of using manual solutions that you must know before using any of them to fix OST file cannot be opened Outlook issue.

However, if you want a hassle-free and professionally tested instant solution, then you can check out the upcoming section.

Fix Unable to Open OST File in Outlook Error Professionally

Now, we know all the manual solutions to fix the Outlook not able to open OST file issue. However, these methods have drawbacks that usually work only when the error is minor, are not easy for non-tech users, and have a risk of account corruption. In such cases, you can try BitRecover OST Recovery Wizard. Using this program, you can simply recover your OST file and make it re-accessible. You can also convert OST files to PST format without requiring Microsoft Outlook and an internet connection by using the same wizard. This program maintains complete data integrity during the recovery and conversion process. So, you don’t need to worry about data integrity.

Download Now Purchase Now

Below are the steps for using the recommended program. Follow the listed steps carefully and fix the “OST file cannot be opened Outlook” error effectively.

Quick Steps of Professional Solution

Open the tool on your Windows Operating System and click “Next.”
Select an option between “select folder” or “select file” and click “Next.”
Now, choose the folders you want to recover from the preview panel of tool and hit “Next.”
Then, select the “saving option” and set “destination path.”
Finally, click on “Repair” button to start fixing.
Done! Your OST file cannot be opened Outlook issue will be solved in a few minutes.

Useful Features of Professional Solution

This tool recovers your OST files without any limitations within a few clicks.
Software provides multiple saving options helps users convert their OST files into other file formats, such as PST, PDF, MSG, EML, and MBOX, etc.
Users can recover corrupted, damaged, and inaccessible OST files in bulk using the same tool.
Its user interface makes it easy to use for both tech and non-tech users, which is why even new users like to use it.
The tool can recover data from encrypted, compressed, or oversized OST files without data loss.
It preserves folder hierarchy and data integrity during the entire recovery process.

These were the useful features of a professional solution that help you to resolve the Outlook OST file cannot be accessed error.

Final Thoughts

In this blog post, we explained the core reasons of OST file cannot be opened Outlook issue. Due to which users are unable to open OST file in Outlook. We provided detailed eight manual solutions to fix OST file not opening in Outlook issue and a professional solution for quick recovery. However, when we are using manual solutions to fix Outlook OST file cannot be accessed error, we found the manual solutions are time-consuming, risky, not useful for non-tech users and fix minor issues.

On the other hand, the recommended professional solution resolve Outlook not able to open OST file problem safely, and instantly without losing data. It also preserved the folder hierarchy, metadata and attachments of the entire OST file data. Now, it’s on you which solution you are going to take for your OST recovery.