Resolved-Outlook OST File Cannot Be Opened Windows 11/10

🕔 9 minutes read
Written By
Updated On


Encountering an error message OST file cannot be opened while working on Outlook offline mode?  Means your Outlook OST files have become inaccessible. If you are facing trouble opening OST file and your important data is at stake, you are at the right place. Follow the write-up and find answers all the queries related to OST file and fix the error easily.

Fix OST file cannot be opened error

Everyone knows an OST file (.ost) is also meant for offline usage in Microsoft Outlook. When you create an Outlook profile, a copy of your Outlook information is stored on your computer until it syncs to the server. This feature makes it possible for the user to work offline when you are not connected to the internet to the server.

Quick Navigation

Why OST files cannot be opened?

How to Fix the Error Cannot Open Outlook OST File?

Does ScanPST works on OST file?

Delete and Recreate the OST file

Why should you convert OST to PST?

Fix OST File Not Opening by Converting OST to PST File

Frequently Asked Questions

The functionality of OST file might look easier. However, there is a major drawback too. Just like any other computer file, an OST file is not immune to corruption. When OST file gets corrupted various error, messages get displayed on the screen. One of the prominent errors that could be seen is cannot open outlook OST file as seen below.

Outlook OST file cannot be opened

Why OST files cannot be opened?

Reasons behind OST file corruption that leads to OST file cannot be opened error are listed below:

  • Abrupt termination of Outlook results in OST file corruption and can make OST file inaccessible.
  • The Outlook application itself may freeze or shut down abruptly and lead to OST file cannot be opened in Outlook
  • Intermittent connectivity due to faults in network cards, cables, routers and other similar devices that affects the functionality of the Outlook and fails to access.
  • Bad sectors on the hard drive affect the functionality parameters and refuse to open Outlook data file.
  • Unexpected power surge sometimes results in inapt functioning of OST file

When Outlook is severely corrupted it is reflected on the files stored in it and displays an error OST File Cannot Be Opened.

How to Fix the Error Cannot Open Outlook OST File In Outlook 2021 and Other Older Versions?

You can fix the OST file issue including the error outlook file OST cannot be opened using manual approaches explained below.

Before heading to next sections lets us try fixing the error with few basic troubleshooting steps like-

  1. If the problem is with the connecting devices, it is recommended to check the network connections and devices to ensure that they are working as per the standards
  2. Functionality of Outlook is enhanced using add-ins but faulty add-ins may sometimes create more trouble. Therefore, find the faulty add-ins and disable them by launching the Outlook in safe mode.
  3. To Start Outlook in Safe mode all you have to is just type outlook /safe in the Run dialog box. Try Save and Send and if it works, a faulty add-in is the main reason behind the error.

You can find the steps related to basic workarounds more briefly under solutions to the most common Outlook errors.  If none of the above mentioned methods worked for you, follow the next methods.

Method 1: Use Task Manager to stop the Outlook related processes

  1. Close MS Outlook program.
  2. Right-click on the Taskbar menu –> Click on Task Manager.
  3. Go to the Processes tab –> Search for the processes Communicator, Lync, Outlook or Ucmapi. If you find any of these processes, select it and click on End Process button.

Method 2: Disable the Outlook Cached Exchange Mode

  1. Close MS Outlook –> Go to control panel
  2. Click on Mail option –> Select Email Accounts.
  3. Next, go to click on Email tab.
  4. Now click on Exchange account and then on Change.
  5. Uncheck the Cached Exchange Mode option under offline settings and Enter Next to finish the process.

Method 3: Repair OST file with ScanPST.exe

Microsoft provides the inbuilt OST and PST Integrity Check tool i.e. called ScanOST.exe and ScanPST.exe that helps to fix minor corruptions in Outlook data files.

Repairing corrupt OST file with ScanOST.exe could be an easy way to fix Outlook.ost cannot be opened error. However, this Outlook inbuilt utility is available with Outlook 2007 and lower versions only. Hence, from the next versions, ScanPST.exe is used to check the integrity of the Outlook data files regardless of OST or PST.

Does ScanPST works on OST file?

Yes, with the help scanpst.exe OST data file can be repaired. Whenever an OST file doesn’t open due to any corruptions, scanpst.exe is triggered automatically. This tool has an ability to open, view and repair corrupted and damaged OST files.

To run ScanPST.exe, first you need to locate the tool. Find your Inbox repair tool  and click on Start button to initiate the scanning process. Finally click on the Repair button to rebuild the Outlook profile.

Even after performing repair using scanpst.exe if you are unable to fix an error OST file cannot be opened, then it should be understood that your OST file has been severely corrupted and scanpst.exe cannot work on it. You can try deleting and recreating the OST file.

Delete and Recreate the OST file

To delete the OST file and recreating it, follow the below steps:

  • If you are aware of the location of your OST file, close Outlook and delete the OST from your system.
  • If you are not aware of the location of an OST file, enter %LOCALAPPDATA%\Microsoft\Outlook\ in Windows Search and press Enter. You will be taken to the folder where the OST is located.
  • After deleting the OST file, start Outlook. Outlook will automatically recreate OST on your system.
Difficulties with Scanpst.exe
  • Scanpst.exe doesn’t guarantee data integrity and security
  • It works good only for minor corruptions
  • The inbox repair tool works directly on the original Outlook data file, hence chances of OST file getting damaged is high
  • Scanpst.exe stops working if the file is severely corrupted or large and consumes much of your time.

Even after performing scanpst.exe if you are unable to fix an error OST file cannot be opened, then it should be understood that your OST file has been severely corrupted and scanpst.exe cannot work on it.

Hence it is recommended to convert OST file to PST file for an easy repairing process and fix OST file cannot be opened error without any hassle.

Why should you convert OST to PST?

In OST, data is stored in MS Exchange Server and any problem with the server directly reflects on OST file. Whereas PST files are stored on client's hard disk. Even if server fails user can easily access data in PST file.

OST files can be accessed only with Exchange Server whereas PST is compatible with other servers. One converted into PST, access your Outlook data from any server.

Converting OST to PST helps in getting back all the Outlook data like emails, calendar information, contacts etc.

Once if Exchange Server crashes down, you cannot recover OST data until you repair it. In order to use the mailbox data of the OST file in online mode, you can convert OST file to PST format and access the data stored in Outlook.

SFWare Convert OST to PST is a proficient conversion tool capable of resolving severe corruptions in the OST file structure by reorganizing OST data file into PST file format. Besides fixing the OST file error, the tool also recovers lost data from its attributes such as emails, tasks, contacts, notes, RSS feeds, etc. Download the software now and try it for free..

Free Download for Windows

How to Repair Outlook OST File Not Opening By Converting OST to PST File?

To Fix OST file cannot be opened download and install SFWare convert OST to PST software. Launch the application.

  1. In the main screen two options are displayed “Open OST file” and “Find OST file”

Open OST file: This option is to repair inaccessible, corrupt or damaged Outlook OST file
Find OST file: This option is used for automatically finding the OST file

Find OST to Convert

  1. Select a drive to search OST file if it is not found in default store locationConvert OST toPST
  2. The software will start the OST to PST conversion and generates a healthy PST file. Select the destination to save the converted file.Converting OST file generates the healthy OST file
    Now, once you have converted your OST to PST, try opening a file and verify your file is free from error OST file cannot be opened.

Frequently Asked Questions

What causes OST file cannot be opened error?

There are several reasons that can cause the error. A few of the main reasons are interrupted termination while working on Outlook data file, connectivity issues that fails to access the OST file and bad sectors on the drive also leads to error.

How ScanPST helps fix OST file error?

Yes, with the help of ScanPST (Inbox repair tool) you fix minor problems in Outlook data files including OST file. It is an inbuilt tool by Microsoft Outlook to fix minor problems in Outlook data files.

Does Recreating OST file fix the OST error cannot be opened?

Sometimes, even after using Inbox repair tool to fix an error OST file cannot be opened error won’t be resolved. This is because, OST file has been severely corrupted and scanpst.exe cannot work on it. in such situation, you can try deleting and recreating the OST file. This method surely help you fx Outlook OST file errors.

Related Posts:

Leave a Reply

Your email address will not be published. Required fields are marked *