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Fix Outlook using an Old Copy of your Outlook Data File (.OST)

  Mark Regan
Mark Regan
Published: April 29th, 2025 • 7 Min Read

When launching Outlook then they show error Outlook using an Old copy of your Outlook data file(OST) can be frustrating. The issues mostly happen when Outlook cannot properly configured ,not synchronized or OST file get corrupted. Due to this, you may face missing emails, outdated folders or not able to access your whole mailbox.

In this tutorial, we will explain about understanding errors, causes of this error and also share valuable approaches to fix Outlook using old copies of data files and prevent them. Whether you are using Outlook for work or personal communication, addressing this error quickly is crucial to maintain security and continuity of your email data.

Table of Contents Hide
  1. Understanding
  2. Causes of Outlook using Old Copy of Data File Error
  3. Fix Outlook using an Old Copy of your Outlook Data File (.OST) Error
  4. Resolve Outlook by Using an Old Copy of Outlook Data File Error
  5. Typical Questions
  6. Preventive Measures
  7. Overall Reflection

Understanding Outlook is Using an Old Copy of Outlook Data File Error

The Outlook error message indicated that your OST file is outdated or get corrupted. Instead of addressing latest synchronized data from mail serer, Outlook refers to a previous or incomplete copy available on your local computer.

  • Missing or outdated emails.
  • Incomplete folder structures
  • Synchronized with email servers.
  • Potential risk of data loss if not corrected.

Typically this error message appears when system crashes, forced shutdowns , synchronization interruption or data file corruption. Recognizing the root cause is crucial for choosing the right fix and restoring normal Outlook.

Causes of Outlook using Old Copy of Data File Error

  • If the Outlook OST file gets corrupted, Outlook may revert to using an older version of the data file.
  • When an OST file grows too large, it can slow down synchronization and lead Outlook to access an outdated copy instead of updating from the mail server.
  • Having a duplicate OST file available on default location can confuse Outlook to detect the correct OST file.
  • Unstable connectivity can stop mailbox synchronization with the server and it may force Outlook to rely on the last synchronized OST file.
  • A corrupted or incorrectly configured Outlook profile can prevent applications from linking to correct or updated data files.

How to Fix Outlook using an Old Copy of your Outlook Data File (.OST) Error?

Resolving “Outlook is using an old copy of your Outlook data file” error involves repairing, recreating, or replacing problematic Outlook data file. Here are several effective methods:

Method 1. Locate and Delete OST File

  1. Close “Outlook” completely.
  2. Navigate to “OST file location” from default location: C:\Users\YourUsername\AppData\Local\Microsoft\Outlook\
  3. Delete OST file and restart Outlook to rebuild OST file and synchronize from server.

Method 2. Set New OST File as Default

  1. Open “Outlook” and navigate to the file.
  2. Click on “Account Settings” and hit on Account Settings again.Press Account Settings
  3. Under data files select the “correct OST file” and set it as default.Select correct OST file
  4. Restart Outlook to apply changes.

Method 3. Create New Outlook Profile

  1. Go to the “Control Panel” and Select Mail.Select Mail(Microsoft Outlook)
  2. Now, Click on Show Profiles and click on “Add to create New profile”.Click on Show Profiles
  3. Configure your email account and set a “New profile as default”.

Method 4. Exit Outlook and Restart Computer

Sometimes, simply close Outlook and restart your machine that can refresh Outlook file connection and resolve data file minor issues.

Method 5. Recreate OST File

  1. Delete “existing OST file”.
  2. Open Outlook and it will “create a fresh OST file” from server data.

Alternative Method: How to Resolve Outlook by Using an Old Copy of Outlook Data File Error?

If the previously manual method doesn’t work, then you need to opt for BitRecover OST to PST Converter, as this software can export to a PST file, and you can easily import the PST file into Microsoft Outlook by using its native import/export feature. This software has been tried and tested to convert corrupted, inaccessible, and orphaned OST files. To use this utility, simply click on the download button and follow the installation instructions, and after installation, follow the guidelines as we have explained below:

Steps to Fix Outlook is Using an Old Copy of your Data File:
  1. Download and install OST Converter on your system then launch it.Launch recommended software
  2. Now, click on convert Configured Outlook mailbox data.Configured Outlook account
  3. After that, Browse Outlook mailbox folder or subfolder as you wish to convert.Choose Outlook mailbox folders
  4. Here, Choose PST option in the list of Saving Option.Choose PST file
  5. Now, Choose PST configuration settings such as separate PST or split PST change language, ignore system folder hierarchy as per required.Set PST Size
  6. Choose the destination path and click on Convert to successfully fix Outlook using the old Copy of Outlook data file.Fix Outlook using an Old Copy of your Outlook Data File (.OST)
Import PST to Microsoft Outlook
  1. Now, you can open “Microsoft Outlook” and navigate to the file.
  2. Click on open and export and choose “Import/Export”.Click on open and export
  3. Now, Select “Import from another program or file” then click on Next.Import from another program or file
  4. Here, Choose “Outlook Data File(.PST)” and hit on Next button.Select Outlook data file
  5. Browse the “My Outlook data file” as you want to export.Select my Outlook data file
  6. Click on the destination path and press “Finish” to get the result quickly.
Paramount traits of Automated Software
  • It allows you to convert OST to CSV, EML, PST, PDF and many more saving features.
  • This software has been perfectly designed for both professional and individual users without depending on any technical expertise.
  • You can also import OST to Thunderbird, Gmail, Zimbra, Outlook.com and all IMAP Supported servers.
  • With this wizard, you can also use filter options such as Create PST year wise, date range, from, to, subject, exclude folders, organizer, root folder and many more.
  • This software can also extract attachments, email addresses and extract contacts from OST file.
Typical Questions about Outlook using Old copy of Data File

Why is my Outlook data file OST instead of PST?

Outlook creates an OST file when you set up an Exchange, Office 365 or IMAP account. It stores a synchronized copy of your mailbox on your device, allowing offline access to PST files used for POP accounts or when manually exporting data.

How to Use an old OST file in Outlook?

You cannot directly open an OST file in Outlook. To access its data, you must convert the OST file using suggested software. Once converted, you can import the PST file into Outlook using the inbuilt Import/Export feature.

How to Use an Existing Outlook Data file?

To use an existing Outlook data file, Open Outlook and navigate to file and click on Open and Export and select Outlook data file and browse path and select it. This file will appear in your Outlook profile, allowing you to access all saved emails and folders.

Preventive Measures for Outlook using an Old Copy of your Outlook Data File (.OST)
  • Take regular backup of Outlook data file to avoid data loss in case of file corruption.
  • Check OST files regularly and archive old emails to maintain OST file size and prevent it from being oversized OST file.
  • Use reliable and consistent connectivity to avoid synchronization interruptions that can damage data files.
  • Always update the Outlook version and your operating system to the latest version to up to date with security patches and bug fixes.
Overall Reflection

In this guide, we have shared the way to fix Outlook using an old copy of your Outlook data file. As it can be a frustrating issue, but with the right instructions, you can resolve it and check the Outlook function smoothly. From deleting and recreating your OST file to create a new Outlook profile or using recommended software to fix it completely . Additionally, we have also shared preventive measures to stay away from this type of error and maintain your healthy Outlook data file(OST) in the long run.