How to Repair OST File - A Complete Guide

Apr 9, 2024 | By Deepak Singh Bisht

In the realm of email management, the integrity of data files is paramount, especially when dealing with Microsoft Outlook's Offline Storage Table (OST) files. These OST files are indispensable for users who need to access their emails and work offline, syncing back with the Exchange server once online. However, encountering a corrupt OST file can halt productivity, leading to the urgent need for a reliable OST repair solution. Whether the cause is hardware malfunctions, software glitches, or malicious attacks, the ability to repair OST files is crucial to ensure the seamless operation of your email client. This comprehensive guide will navigate you through the process of utilizing both built-in tools and specialized OST file repair tools designed to fix and repair corrupt OST files effectively. By integrating the use of an Outlook OST repair tool, this guide aims to equip you with the knowledge to restore access to your critical emails and data, ensuring your communication workflow remains uninterrupted.

What is an OST File?

An OST file, short for Offline Storage Table, is a type of data file used by Microsoft Outlook that allows users to access their email messages and work offline. Essentially, it is a copy of a user's Exchange mailbox stored on the local computer. This functionality is particularly useful in environments with intermittent internet connectivity or for users who need to manage their emails outside of regular network access.

When working in Outlook's offline mode, any actions you take—such as reading emails, drafting responses, or organizing your mailbox—are saved to the OST file. Then, once you reconnect to the internet, Outlook synchronizes the offline changes with the Exchange server, ensuring that your mailbox is up-to-date both online and offline.

The OST file format enables several critical functionalities:

Offline access: Users can continue working with their emails and calendar entries even when there's no network connection. Once the connection is re-established, all changes synchronize with the server.

Data sync: It ensures that any changes made while offline are automatically updated in the Exchange server once the connection is restored, keeping the mailbox consistent across different devices.

Disaster recovery: In cases where the server encounters issues, the data stored in OST files can act as a backup, allowing users to recover their information.

Why do OST files get corrupted?

OST files, while critical for enabling offline access to Microsoft Outlook data, are susceptible to corruption. Understanding the common reasons behind OST file corruption can help in preventing potential data loss and ensuring smooth operation. Here are some of the primary factors that can lead to OST file corruption:

Hardware failures: Issues with the hardware components of your computer, such as a failing hard drive, can corrupt the OST file stored on it. Sudden power surges or improper shutdown processes can also cause file corruption.

Software errors: Software glitches within Outlook or operating system malfunctions can lead to improper handling of OST files, thereby corrupting them. Incompatible or buggy add-ins and plugins might also interfere with how Outlook accesses and syncs the OST file.

Network connection issues: Since OST files sync with the server when a network connection is available, any interruptions or instability in the connection during synchronization can lead to file corruption. This is particularly common in environments with unreliable or slow internet connections.

Virus or malware infections: Malicious software can target and corrupt OST files as part of its payload. Viruses and malware often seek to disrupt normal operations or access sensitive information, and corrupting an OST file can be a method of achieving these goals.

Large file size: OST files have size limits, and exceeding these limits can cause performance issues or corruption. As email accounts grow over time, the accumulation of data can push OST files beyond their capacity, leading to problems.

Improper closure of Outlook: Not closing Outlook properly or forcing it to close can corrupt the OST file. This might happen if Outlook is shut down through the Task Manager or if the system crashes while Outlook is running.

Conflict with other software: Occasionally, other software installed on your computer can conflict with Outlook, leading to OST file corruption. This includes security software that might mistakenly identify parts of the OST file as a threat.

Understanding these causes of OST file corruption is the first step in implementing strategies to prevent it, such as maintaining a stable and secure computing environment, keeping software updated, and ensuring regular backups. However, when corruption does occur, it's important to know how to repair the OST file to restore access to your Outlook data.


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How to repair OST file?

When an OST file gets corrupted, there are a couple of standard methods available to repair and restore it. The two primary approaches include manual methods and the use of third-party OST repair tools.

The manual methods usually involve built-in features of the Outlook application, like the Inbox Repair Tool (ScanPST.exe), or recreating the OST file. While these methods can be effective, they can also be quite technical and might not always recover all your data.

On the other hand, third-party OST file repair tools often provide a more user-friendly interface and offer more advanced recovery options, making them a popular choice for many users to repair OST files.

Here, we will delve into each of these methods in detail, providing step-by-step instructions to guide you through the process of repairing OST files.

Note: Before attempting any methods to repair OST files, it's crucial to create a backup of your files. This precaution ensures that your data remains safe in the event of any unforeseen issues during the repair process.

Method 1: Repair OST file using Inbox Repair Tool

The Inbox Repair Tool (Scanpst.exe) provided by Microsoft is designed to repair errors in Outlook data files, including OST files. It scans the file for inconsistencies or errors and attempts to fix them to regain access to your data.

Steps to follow:

1. Close MS Outlook and navigate to one of the following file locations, then double-click on SCANPST.EXE to open it.

  • Outlook 2019: C:\Program Files (x86)\Microsoft Office\root\Office16
  • Outlook 2016: C:\Program Files (x86)\Microsoft Office\root\Office16
  • Outlook 2013: C:\Program Files (x86)\Microsoft Office\Office15
  • Outlook 2010: C:\Program Files (x86)\Microsoft Office\Office14
  • Outlook 2007: C:\Program Files (x86)\Microsoft Office\Office12
Displaying file location paths for SCANPST.EXE

2. Once the tool is open, click on the 'Browse' button.

Opening SCANPST.EXE tool in Outlook.

3. Select the damaged OST file you wish to repair and click on the 'Open' button.

Browsing for damaged OST file in SCANPST.EXE.

4. After selecting the file, click on the 'Start' button.

Initiating file repair with Start button in SCANPST.EXE.

5. SCANPST.EXE will then check the file for consistency and issues.

SCANPST.EXE checking file consistency.

6. If SCANPST.EXE detects errors, choose the 'Make backup of scanned file before repairing' option, select a backup location, and click 'Repair' to start the repair process.

Selecting backup option in SCANPST.EXE before repair.

7. Upon completion, a 'Repair Complete' popup will appear; click 'OK' to conclude the process.

Repair Complete notification in SCANPST.EXE.

After the process, you might see the Recovered Personal Folders or Lost and Found folder. These folders contain your missing folders and items. To place the items in the original folder structure, you can select items, and after that, drag the selected items and drop them into the original folders.

When to use:

  1. For minor errors and inconsistencies in your OST file.
  2. When Outlook is experiencing issues opening, or you're receiving error messages related to the OST file.
  3. As a first step in OST file troubleshooting, before trying more complex solutions.

Method 2: Repair Outlook OST file by deleting and recreating the OST file

This method involves deleting the corrupted OST file and allowing Outlook to recreate a fresh copy. This process can resolve issues caused by OST file corruption.

Steps to follow:

1. Open MS Outlook and navigate to the File menu.

Accessing File menu in MS Outlook

2. Choose 'Account Settings' and then select the 'Account Settings' option.

Selecting Account Settings in MS Outlook.

3. The Account Settings window will open, displaying your currently connected email accounts.

Display of connected email accounts in Outlook Account Settings.

4. Click on the 'Data Files' tab and select the OST file you wish to recreate.

Choosing OST file under Data Files tab in Outlook.

5. Choose the 'Open File Location' option to view the OST file's location.

Opening OST file location from MS Outlook.

6. After locating the OST file, close MS Outlook.

7. Identify the OST file you intend to recreate.

Identifying OST file for recreation in Outlook.

8. Right-click on the chosen OST file and select the 'Rename' option.

Renaming OST file in file explorer.

9. Append the .bak extension to the end of the OST file name and press the Enter key.

Adding .bak extension to OST file name.

10. Reopen MS Outlook.

Reopening MS Outlook for setup.

11. Outlook will automatically recreate the OST file.

Automatic recreation of OST file in Outlook.

When to use:

  1. When the Inbox Repair Tool is unable to fix the OST file.
  2. If the OST file is too damaged for standard repair methods.
  3. After ensuring that all your data is synchronized with the Exchange server to prevent data loss.
  4. Particularly useful when facing synchronization issues or severe file corruption.

Note: This method pulls data from the MS Exchange server. It cannot restore Outlook items that you created in Offline mode and was not synched with MS Exchange.

Method 3: Fix OST file by disabling and re-enabling Cached Exchange Mode

Cached Exchange Mode in Outlook allows you to work offline with a copy of your mailbox. Disabling and then re-enabling it can reset the synchronization with the Exchange server, potentially resolving issues.

Steps to follow:

  1. Close Outlook and go to Control Panel > Mail.
  2. Click on Email Accounts and select your Exchange account.
  3. Uncheck the option 'Use Cached Exchange Mode'.
  4. Apply the changes and reopen Outlook to let it synchronize.
  5. Repeat the steps and re-enable Cached Exchange Mode.

When to use:

  1. When experiencing synchronization problems between Outlook and the Exchange server.
  2. If new emails aren't appearing in Outlook or changes aren't syncing.
  3. After encountering errors suggesting problems with the OST file's integrity.

Method 4: Repair OST file using the OST Integrity Check Tool (Scanost.exe)

Scanost.exe was a tool available in older versions of Outlook (up to 2007) designed to check and repair issues within OST files. It's less powerful than Scanpst.exe but useful for minor integrity issues.

Note: This tool is not available in newer versions of Outlook.

Steps to follow:

  1. Close Outlook and locate Scanost.exe (usually in the same directory as Scanpst.exe).
  2. Run the tool and select the profile containing the OST file.
  3. Choose the option to repair errors and start the scan.

When to use:

  1. With older versions of Outlook (2007 or earlier).
  2. When experiencing minor issues with OST files, like minor synchronization errors.

Method 5: Repair Outlook OST File by Resetting Outlook Profile

Creating a new Outlook profile can resolve issues caused by a corrupt profile. It essentially resets Outlook's settings and files, potentially fixing problems related to the OST file.

Steps to follow:

  1. Close Outlook and go to Control Panel > Mail.
  2. Click on 'Show Profiles'.
  3. Add a new profile and configure it with your email account.
  4. Set the new profile as the default profile.
  5. Restart Outlook and check if the issues are resolved.

When to use:

  1. If problems persist even after repairing the OST file.
  2. When Outlook continuously crashes or fails to start.
  3. If OST-related errors continue after other repair attempts.

Method 6: Fix OST file utilizing Windows System Restore

Windows System Restore can revert your system to a previous state where Outlook and the OST file were functioning correctly. It's helpful if a recent system change caused the OST file issues.

Steps to follow:

  1. Go to Control Panel > System and Security > System.
  2. Click on System protection and then System Restore.
  3. Follow the prompts to choose a restore point before the issue started.

When to use:

  1. After a software installation or system update coincides with the start of OST file problems.
  2. If changes to system settings have affected Outlook's performance or file integrity.
  3. As a last resort when other methods haven't resolved the issue.

Method 7: Repair OST file using OST Repair Tool

If your OST file is still inaccessible after trying the above methods, you might consider using a third-party Outlook OST Repair tool like SysCurve OST to PST Converter to repair OST file. This software is designed to repair and recover damaged OST files and convert them into PST format, making your data accessible in Microsoft Outlook.

  1. Download and install the OST Repair tool
  2. Click on the Add file and select the OST file which you want to repair
  3. Click on the Scan button and click on the OK button
  4. After the process, the software will generate a preview mode inside the software
  5. Click on the Export and choose the Export All folders option
  6. Select PST (Outlook data file) as an Export option and provide a destination path
  7. Click on the Next button to start the conversion process

After the process, you can open the converted PST file with MS Outlook.

Other Helpful Features

  • Quickly repair OST files.
  • Converts OST to PST, EML, MBOX, HTML, RTF, and other file formats.
  • Migrates OST to Office 365 and Live Exchange server.
  • Maintains the original folder hierarchy structure.
  • Performs selective conversion based on To, From, Subject, Cc, Date range, etc.
  • Offers free conversion or migration for the first 20 items per folder.
  • Supports Windows OS and all versions of MS Outlook.

Frequently Asked Questions

What are the signs that my OST file is corrupted?

The signs of OST file corruption typically include difficulties in opening Outlook, errors during synchronization with the Exchange server, missing emails that you know should be there, and frequent crashes of the Outlook application. These symptoms suggest that the OST file might be corrupted and in need of repair.

How do OST files become corrupted?

OST files may become corrupted for several reasons, including hardware failures, software errors, network connection issues, virus or malware infections, exceeding the OST file size limits, improper closure of Outlook, and conflicts with other software. Understanding these potential causes is essential to prevent data loss and ensure Outlook runs smoothly.

Can OST files become oversized, and how does it affect performance?

Yes, OST files can become oversized, which may lead to a decrease in Outlook's performance. Large OST files can cause Outlook to operate more slowly, respond sluggishly, or even crash. To avoid these issues, it's recommended to regularly archive old items and keep the OST file size manageable.

How can I ensure my OST file doesn't get corrupted?

To minimize the risk of OST file corruption, maintain a stable and secure computing environment, regularly update your software, avoid exceeding the OST file size limit, ensure proper closure of Outlook, and regularly back up your OST file. Also, be cautious of network stability during synchronization and be wary of potential conflicts with other installed software.

Is there a size limit for the OST file to be repaired?

While manual repair methods might struggle with larger OST files, third-party software such as the SysCurve OST Repair tool is designed to handle OST files of any size. This capability makes it an ideal solution for repairing large OST files without size limitations.

Can I repair corrupted OST files from Outlook 2016 and 2019?

Yes, corrupted OST files from Outlook 2016 and 2019 can be repaired. You have the option to employ manual methods provided by Microsoft, such as using the Inbox Repair Tool (ScanPST.exe), or to utilize third-party software for potentially more comprehensive solutions. The SysCurve Outlook OST Repair tool is one such third-party solution that offers a straightforward approach to repairing OST files.

Are there any limitations to repairing an OST file?

Yes, there are limitations to repairing an OST file. The success of the repair process heavily depends on the level of file corruption and the repair method employed. While manual repair methods may not always successfully recover all data, especially in cases of severe corruption, third-party tools such as the SysCurve Outlook OST Repair tool often provide a more comprehensive recovery solution and are capable of repairing OST files more efficiently.

What if the manual method to repair an OST file does not work?

If the manual repair methods fail or appear too complex, third-party tools like the SysCurve OST File Repair tool offer an alternative solution. These tools provide a simpler, user-friendly approach to repairing corrupted OST files, along with advanced features that may not be available through manual repair techniques. They can be especially useful for handling more severe cases of file corruption.

Are there any free OST repair tools available to repair OST files?

There are no free third-party Outlook OST repair tools that offer full functionality. However, Microsoft provides the Inbox Repair Tool (ScanPST.exe) as a free option for repairing OST files. This tool can be effective for some issues but might not offer comprehensive repair capabilities for severely corrupted files. For more advanced repair and recovery needs, investing in a reputable third-party tool may be necessary.

Is it safe to use a third-party OST Repair tool to repair OST files?

Using a third-party Outlook OST Repair tool can be safe. It is important to select a trusted tool like the SysCurve OST File Repair tool, which guarantees the safety and security of your data during the repair and conversion process. Always research and ensure the software comes from a reputable provider to avoid potential risks to your data.

Can I convert an OST file to another format?

With the SysCurve OST repair tool, you indeed can convert OST files to various formats, including PST, EML, MBOX, HTML, and RTF. This feature is especially useful for accessing your Outlook data in other applications or ensuring your backups are in formats that are widely accessible and easy to manage.

Does the SysCurve Outlook OST Repair tool come with a demo version?

Indeed, the SysCurve OST File Repair tool offers a demo version, allowing users to experience its capabilities firsthand. With the demo version, you can repair a corrupted OST file and convert it into formats such as PST, EML, MSG, MBOX, among others. It's important to note, however, that the demo version is limited to converting the first 20 items per folder. This limitation gives users a preview of the tool's functionality before committing to a purchase.

The Final Word

Navigating the complexities of OST files in Microsoft Outlook requires a keen understanding of their importance, functionality, and the common pitfalls that can lead to corruption. Whether caused by hardware malfunctions, software glitches, network issues, or other external factors, a corrupt OST file poses a significant barrier to effective email management and productivity. However, equipped with the knowledge from this comprehensive guide, repairing a corrupt OST file becomes a manageable task, ensuring the seamless operation of your email client remains within reach.

Utilizing the right tools and techniques, such as the Inbox Repair Tool (ScanPST.exe) for minor issues or the SysCurve Outlook OST Repair tool for more severe cases, allows for the effective recovery and restoration of crucial data. Moreover, the capability to convert OST files into other formats opens up avenues for data access across various applications, ensuring that your communication workflow remains uninterrupted regardless of the platform.

Remember, the key to preventing OST file corruption lies in regular maintenance practices, such as keeping your software up-to-date, managing file size, and ensuring proper shutdown procedures are followed. In addition, being prepared with regular backups can provide an invaluable safety net against potential data loss.

In conclusion, although OST file corruption presents a challenge, it can be overcome with the correct approach and tools at your disposal. Whether through manual methods or leveraging the power of an Outlook OST repair tool like SysCurve, your ability to repair OST files effectively ensures that your Outlook data remains accessible, secure, and fully integrated into your daily workflow.

The Author

Deepak Singh Bisht

Deepak Singh Bisht

Content Lead |

Deepak Singh Bisht is a dedicated IT professional with over 9 years of experience, is a key member at SysCurve Software for the last 5 years. His expertise lies in email migration and data recovery, with a focus on technologies like MS Outlook and Office 365. Deepak, who also delves into front-end technology and software development, holds a Bachelor's degree in Computer Applications.

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