Exactly Why Did Being OST File Not Open in Outlook?

Simple Solution for OST File Not Open in Outlook

This post provides a simple solution for OST File Not Opening in Outlook that will assist you in resolving these issues. We’ve detailed the easiest way to deal with this problem and recommended a reputable OST to PST converter for recovering and converting OST files to PST format. Continue reading for more information.


Knowing the OST File

An Outlook Offline Storage file, or OST for short, is simply an exact local duplicate of the mailbox kept on the computer user’s device, allowing offline access to emails, contacts, calendar items, and other Outlook data. Emails in this format may be authored, read, and organized even while not connected to the Internet. Once back online, any changes made to the OST file are automatically updated by the Exchange server, ensuring that data shared across devices remains synced.

Why isn’t your OST file opening in Outlook?

There might be various reasons why your OST file does not open in Outlook:

  • Corruption: OST files can get damaged owing to a variety of reasons, including unexpected system failure, program conflicts, hardware failure, or virus infection. Corruption can make it unavailable, preventing Outlook from opening it.
  • Outlook profile issues: A damaged Outlook profile or an issue with the application’s settings may prevent you from using OST files. Incorrect account configuration or other problems with Outlook components might disrupt the smooth execution of OST files.
  • Server Connectivity Issues: while there is a problem connecting to the Exchange server or the network, Outlook may cease syncing with the server, resulting in issues while opening OST files.
  • Large File Size: OST files gradually accumulate a large amount of data, which exceeds the size constraints. Exceeding this limit may result in performance difficulties and make it difficult to access the OST file in Outlook.
  • The program was upgrades or Compatibility difficulties: Outlook upgrades or changes to the program environment can often cause compatibility difficulties with existing OST files. The Outlook version may be incompatible with the OST file structure, causing the OST file to not open in Outlook.

How Can I Fix the OST File Not Opening in Outlook?

The resolution of the OST file that cannot be opened in Outlook must be done methodically.

1. Run the OST Integrity Check.

Outlook features an “OST Integrity Check” or “ScanOST” (for previous versions) function built in that can assist fix damaged OST files. This utility scans the OST file for mistakes and attempts to correct them automatically.

  1. Close Outlook and activate the Control Panel.
  2. Select the appropriate “Mail” or “Mail and Email Accounts” option for your Windows version.
  3. Navigate to the “Data Files” menu and choose the OST file to repair.
  4. To access the scanning and repair wizard, choose “Settings” and then “Repair”.

2. Check Server Connectivity

Make that your PC has a decent internet connection and can connect to the Exchange server. Confirming the server settings in Outlook and troubleshooting any network issues that may be interfering with connectivity.

3. Decrease OST file size.

If the OST file is large, consider deleting older emails or compressing it to reduce its size. In Outlook, you may use the functionality to archive emails to a separate PST (Personal Storage Table) file, which helps you manage the size of the OST file.

4. Update Outlook, Windows, and macOS

Make sure you have the most recent patches and upgrades for both Outlook and Windows. Microsoft provides patch updates regularly to address bugs, security vulnerabilities, and compatibility issues, which might result in OST files not opening in Outlook. It also supports all the latest Mac OS versions.

Unfortunately, there is no official solution, however we recommend utilizing Mailvita OST to PST Converter Software. It’s an excellent tool for converting OST files of any size in a single step, without mistakes. Recover and repair the corrupted Outlook Offline OST files.

Here are the steps for converting OST files to PST: –

  1. Run the program on your Windows machine.
  2. Select the OST files and click the Browse Button.
  3. Ignore empty folders while seeing the preview.
  4. Select a location for saving the converted PST files and click the Browse button.
  5. Click the “Generate Now” button.


We’ve offered the correct remedy for when an OST file won’t open in Outlook, whether due to missing updates, defective add-ins, damaged OST files, or other difficulties. This issue may be easily resolved by following the procedures outlined here. If your OST file becomes inaccessible, you may use professional software, such as OST to PST Migrator, to extract the contents. The application converts OST files to PST format, which can then be imported into any Outlook account or profile.