Microsoft Outlook uses data files such as PST (Personal Storage Table) and OST (Offline Storage Table) to store emails, contacts, calendars, attachments, and other mailbox information. Sometimes, while opening Outlook, sending emails, or accessing a mailbox, users may see the error “Outlook data file cannot be accessed” or “Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The file … cannot be accessed.”

This error usually indicates that Outlook cannot properly access its associated PST or OST file. Fortunately, there are several ways to fix the problem without immediately losing your mailbox data.

What Causes the “Outlook Data File Cannot Be Accessed” Error?

Before trying the solutions, it is useful to understand why Outlook cannot access its data file. Common reasons include:

• Corrupted or damaged PST/OST file
• Incorrect Outlook data file location
• PST file moved or renamed
• Outlook profile corruption
• Permission issues with the data file
• Network or synchronization problems
• Large or oversized Outlook data files
• Sudden system shutdown or Outlook crash
• Problems with an old Outlook profile

Identifying the cause can help you choose the most suitable solution.

How to Fix Outlook Data File Cannot Be Accessed Error

1. Check the Outlook Data File Location

The first step is to confirm whether the PST or OST file still exists in its original location.

Open Control Panel > Mail > Data Files and check the Outlook data file associated with your profile. If Outlook is pointing to a file that has been moved, renamed, or deleted, it may not be able to access your mailbox.

If you already know where your PST file is stored, make sure the file is available and accessible from your computer.

2. Run the Inbox Repair Tool (SCANPST.EXE)

If the PST file is damaged, Microsoft’s built-in Inbox Repair Tool, commonly known as SCANPST.EXE, can help identify and repair certain types of PST corruption.

First, close Outlook completely. Then locate SCANPST.EXE in your Microsoft Office or Microsoft 365 installation folder. Select the affected PST file and start the scan.

If errors are detected, choose the repair option. It is recommended to create a backup copy of the original PST before repairing it.

Keep in mind that SCANPST can repair some forms of corruption, but it cannot guarantee recovery from every type of severely damaged PST file.

3. Check File Permissions

Sometimes Outlook cannot access a PST because Windows permissions prevent the application from reading or modifying the file.

Right-click the PST file and select Properties. Under the Security tab, verify that your Windows account has appropriate permissions.

Also check whether the file is marked as Read-only. If necessary, remove the Read-only attribute and try opening Outlook again.

4. Create a New Outlook Profile

A corrupted Outlook profile can also cause the Outlook data file cannot be accessed error.

To test this, open Control Panel > Mail > Show Profiles and create a new profile. Add your email account to the new profile and set it as the default profile.

If Outlook works normally with the new profile, the original profile may have been damaged.

For users with important local PST data, make sure the required PST file is correctly added to the new profile before removing or modifying the old profile.

5. Repair or Recreate the OST File

If you are using a Microsoft Exchange, Microsoft 365, or IMAP account, Outlook may use an OST file to store an offline copy of mailbox data.

If the OST file becomes damaged or cannot synchronize correctly, recreating it can resolve the issue in many cases.

Close Outlook, locate the OST file, and rename it rather than immediately deleting it. Then restart Outlook. Outlook can generally create a new OST file and synchronize mailbox data again.

Important: Do not delete an OST file blindly if you are unsure whether it contains data that exists only locally.

6. Check Your Outlook Profile and Account Settings

Incorrect account configuration can also prevent Outlook from accessing the correct data file.

Open Outlook account settings and verify that the email account is correctly configured. Also check Account Settings > Data Files to confirm that the correct PST file is selected.

If Outlook is trying to use an unavailable data file, changing the default data file to the correct one may resolve the problem.

7. Move the PST File to a Local Folder

If your PST file is stored on a network drive, external drive, cloud-synchronized folder, or another location that is temporarily unavailable, Outlook may fail to access it.

For troubleshooting, keep the PST file on a reliable local drive and make sure Outlook has continuous access to it.

Avoid storing active Outlook PST files in locations where synchronization or file locking can interfere with Outlook.

What If the PST File Is Severely Corrupted?

If the above methods do not fix the problem and Outlook still cannot access the PST file, the data file may be severely corrupted.

In this situation, users may need a dedicated PST repair or recovery solution that can extract mailbox data from damaged files. If the data is important, always create a backup of the original PST before attempting multiple repair operations.

For users who need to migrate, convert, merge, or recover Outlook mailbox data, Way2Migration provides tools designed for different email migration and conversion requirements.

Frequently Asked Questions

Why does Outlook say the data file cannot be accessed?

The error can occur because the PST/OST file is corrupted, unavailable, moved, renamed, inaccessible due to permissions, or associated with a damaged Outlook profile.

How do I repair an Outlook data file?

For a damaged PST, you can first try Microsoft’s Inbox Repair Tool, SCANPST.EXE. Create a backup of the original file before repairing it.

Can a corrupted PST file be recovered?

In many cases, mailbox data can be recovered from a corrupted PST, depending on the extent and type of corruption. If built-in repair tools fail, specialized PST recovery software may be required.

Will creating a new Outlook profile delete my emails?

Creating a new profile does not automatically delete your existing PST file. However, you should back up important PST data before making profile changes.

Conclusion

The “Outlook Data File Cannot Be Accessed” error can prevent users from opening Outlook or accessing important emails and mailbox data. The problem may be caused by PST corruption, an incorrect file location, permissions, a damaged Outlook profile, or OST synchronization issues.

Start by checking the data file location and permissions, then try SCANPST.EXE for PST corruption. If the issue continues, creating a new Outlook profile or rebuilding the OST file may help. For severely damaged PST files, consider a reliable recovery or conversion solution to protect and retrieve your mailbox data.