Repair Error Outlook OST File cannot be Opened

Working offline? Unable to open OST file? Quickly gain access to your emails in OST file by converting it into a PST using Remo convert OST to PST. You are just 4 clicks away from creating a new all accessible PST file without missing mails, contacts, notes, RSS feeds intact.

What is an Outlook OST file?

OST is abbreviation to Offline Storage Table. This Outlook file solves the problem of intermitted or limited connectivity by storing the emails that you work on when even you are disconnected to the mail server and enables an Outlook user to work offline.

Later the OST file is synced to the exchange server and the pending mails are sent when the connectivity is established.

Introduction to Outlook OST file cannot be opened

The main purpose of OST file is to give accessibility to mails even after being disconnected to Microsoft exchange server. Therefore, if you cannot open OST file neither can you access downloaded mails nor sync the offline mails to the server.

Why is Outlook OST file not opening?

ost to pst cannot be opened error

If an error message “OST file cannot be opened” is displayed when you try to open Outlook OST file. You can try to open the OST file by using certain methods such as – starting Outlook OST file in Safe Mode, turning off Compatibility Mode, and so on. If nothing works out and the OST file still refuses to open.


There could be various factors behind OST file corruption. However, this doesn’t mean that you cannot access the OST file again. With the help of Remo Convert OST to PST software, fixing the unable to open OST file error is easy and quick.

Causes for OST File cannot be Opened Error:

  • Improper installation of Outlook
  • Abruptly terminating Outlook when OST file is still in use
  • Interruption while sharing OST file across network
  • Synchronization error between OST file and Exchange Server mailbox
  • Outlook exchange server is deleted and your OST file is orphaned
  • Exit a broadcast group or organization
  • Improper way of importing OST files

Limitations of OST file and the need for OST to PST conversion:

OST file has limitations when compared to a PST file. It cannot be opened from any Outlook profile. OST file needs Outlook to be configured with port settings of the exchange server that has the exact account credentials as the .ost file in order to open it.

Hence it is of utmost difficulty to repair or access .ost file from anywhere. In such circumstances when you try to get local copies of mails from Microsoft Exchange Server, you will not be allowed to access Outlook OST files.

Remo Convert OST to PST a conversion tool capable of resolving severe corruptions in the OST file structure and rearranges data into PST file format to gain accessibility to the mail data. Hence fixing the error using a OST to PST converter is the best way to fix the error OST file cannot be opened.

The methods to fix error “.ost file cannot be opened” can be classified into two categories:

  • Manual Methods
  • Using OST to PST converter

Fixing Outlook OST cannot be opened error using manual methods:

    Scanpst.exe is an inbuilt Outlook data file repair tool. Normally if the OST file ceases to open due to any corruptions Scanpst.exe is triggered automatically and repairs the OST file. In other cases Scanpst has to be run manually.
    For Outlook 2016 if the OST file is not opening, Scanpst.exe can be found in the following path:
    C:\Program Files (x86)\Microsoft Office\root\Office 16
    For Outlook 2013 if the OST file is not opening, Scanpst.exe can be found in the following path:
    C:\Program Files (x86)\Microsoft Office\Office 15
    For Outlook 2007 if the OST file is not opening, Scanpst.exe can be found in the following path:
    C:\Program Files (x86)\Microsoft Office\Office 12
    If the OST file still does not open after being repaired by Scanpst.exe follow these simple steps:
  • Check for Outlook erratic behavior in Task manager:
    Open task manager and check if any Outlook process is interrupting the OST file access. Terminate all Outlook related processes by right clicking on the Outlook process from Processes tab and select End task.
    Restart Outlook and see if the OST file is now opening.
  • Find and terminate any Outlook add-ins obstructing OST file access:
    Third-party Add-ins are a great way to customize and modify your Outlook access. But they also can be the biggest challenges to access OST files. You can find enabled add-ins in the following path:
    File->Options->Add-ins->COM Add-ins, follow this path once you run Outlook as administrator. Uncheck any third party add-ins and check if the OST file can be opened now.

Fixing Outlook OST file cannot be opened error using OST to PST converter:

A quick solution to fix “OST file cannot be opened” error is by using Remo OST to PST Conversion tool.

Why choose Remo convert OST to PST?

  • Fix password protected file or encrypted file.
  • The corrupt OST file is used as a reference and the data is replicated into a new PST file. Hence the original OST file remains untouched.
  • Along with fixing the OST file error, the program also recovers its attributes such as emails, tasks, contacts, notes, RSS feeds, etc which are deleted or lost.
  • Remo Convert OST to PST software to fixes OST files which exceed the file size limit.
  • Convert healthy or corrupted OST file created on Microsoft Exchange 5.0, 5.5, 2000, 2003 etc to Outlook PST
microsoft exchange add in

How to fix Not Opening Outlook OST File:

  • Download and Install Remo Convert OST to PST software
  • ost to pst home screen
  • Launch the software and select Open OST file option to convert or repair default OST file
  • ost to pst select file
  • Select Find OST File if you want to convert and repair any other OST that is not default
  • ost to pst find file
  • Then provide the destination path to save the converted file
  • ost to pst save screen
  • Finally, click on Convert button to start the conversion process
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