How to Resolve OST file won’t open in Outlook 2016

Microsoft regularly rolls out upgrades for Outlook to fix the bugs and enhance/add the features and functions.However, the upgraded versions should be installed properly, else these may result in errors, as in this case of an error spelled out as “OST File won’t open in Outlook 2016”.

The following section narrates an instance of this error faced by an Office user.

A user upgraded from Office 2013 to 2016 version in Office 365. Immediately after the upgrade, the user was unable to sync Outlook with Exchange ActiveSync server, and the result was that Outlook failed to perform its intended functions such as to send or receive emails, calendars or updates.

The user deleted the existing Outlook profile and created a new one to troubleshoot the problem. This activity should have established the connection between the server and the email client, but the matter got worsened, with Outlook displaying the following error message:

Next, the user uninstalled and reinstalled the entire instance of Office 365, but the OST file still couldn’t be opened even after reinstalling the application.

The above incident presented a general outline of the OST file-related issue which seems to have affected a large number of users after they’d upgraded to Microsoft Office 2016 on Office 365.

OST file won’t open in Outlook 2016 – How to solve

Firstly, check if you had created a duplicate account. If yes, then set one of the accounts as default to resolve the ‘OST file won’t open in Outlook 2016’ issue.

If that’s not the case, i.e. there’s no duplicate accounts, proceed with the following methods to solve the issue:

Method 1: Create a Fresh Outlook Profile

Resolve the issue by creating a new Outlook profile for Microsoft Outlook 2016 and sync the account with Exchange ActiveSync server through “Auto Account Setup”. Follow the below-mentioned steps to create a new profile:

  1. Install Outlook application and select File > Account Settings > Manage Profiles
  2. Choose Show Profiles > Add.
  3. The Profile Name box is displayed. Type a name for the profile, and click OK.
  4. Next, select the ‘Auto Account Setup’ instead of ‘Manual Setup’

What actual users had reported on this method?

A user followed all the instructions of Auto Account setup and tested the Outlook connectivity and login credentials at But, when the user tried to open Outlook profile with new OST the same error message got displayed:

Other users also report the same issue even after configuring a new computer with Windows 10 and Office 2016 specifications.

Method 2: Converter OST to PST to solve “OST File won’t open in Outlook”

This method is based on using a software utility for extracting mailbox data from the inaccessible OST file in PST which can be then readily imported in Outlook. The following OST to PST conversion steps are based on using Stellar Converter for OST software:

  1. Launch the software.
  2. Browse and select the OST file
  3. Select the Convert option to initiate the process.
    a) The software scans the OST file and starts OST to PST file conversion process
  4. After a successful conversion, the software previews the converted file
  5. Verify the data, select mailbox items and click Save. Specify the location to save the PST file
  6. Import and open the PST file in any Outlook profile without any limitation.

OST to PST converter software provides a better solution to regain access to mailbox data stored inside OST files that won’t open in Outlook 2016. It’s easier to run (less efforts/resources), gets faster results (saves time), and is more reliable.


Microsoft Outlook is one of the most used email clients in current times, as it meets the changing needs of the user and provides a feature-rich environment. This post highlighted the manual and software-based approach to resolve the Outlook error – ‘OST file won’t open in Outlook 2016’. The error occurs when the user is unable to open the OST file after upgrading Microsoft Outlook. To recapitulate, the manual approach comes as lengthy, time-consuming and unwieldy.

On the other hand, the software-based method outlined for Stellar Converter for OST is straightforward, faster, DIY and precise. The OST to PST conversion process is faster and ensures OST file access after Outlook upgrade.

  1. Henri February 18, 2020
  2. M Henrey October 16, 2019
    • Eric Simson October 16, 2019

Leave a Reply

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

Time limit is exhausted. Please reload CAPTCHA.