How to fix OST File Cannot be Accessed Outlook 2016?

Last updated on October 14th, 2023 at 01:19 pm

OST files sometimes get corrupted due to several factors and cannot be accessed in Outlook 2016. Users often explore the key to solving this obstacle. However, they cannot figure out the solution. There is no need to wander here and there because I brought up all the “explanation components” in only one blog. So that users can fix the OST file errors effortlessly and duly. Continue to read this blog for a complete understanding and Solutions for How to Fix OST files that Cannot be Accessed in Outlook 2016.

User Queries

Query 1.  My Outlook OST file got corrupted and inaccessible through Outlook and now I am unable to access my important emails stored in OST file format. I am looking for a way of fixing OST files. I was advised to use converter software by one of my friends but I don’t know which Software is safest and best for solving the issue. Can anyone give me the ultimate solution to this situation?

Query 2. I cannot open and access the OST file in Outlook. I do not know what happened to the OST file and how the OST file became inaccessible. I need help in opening my OST file safely without the risk of getting lost of any data from the OST file. Does anyone know how to open my OST file in Outlook 2016?

What is an Outlook OST file?

OST is a file format that is used by Microsoft Outlook, the Popular email Client, or personal information manager. The Outlook OST file is associated with the Cached Exchange Mode feature in Outlook, which allows users to work with their Exchange Server, even when they are offline and not connected to the internet or exchange server.

When users use Cached Exchange Mode in Outlook, it creates an OST file on their local computer. This OST file contains a synchronized copy of your mailbox data including (Emails, Calendars, Contacts, Tasks, Notes, Journals, Address bookmarks, and others) from the Exchange Server or Office365 account.

Why and How did the OST file get corrupted?

I have mentioned below various factors that why OST file gets corrupt as follows:-

  • The OST file is used to store the copy of Mailbox items for example: [Inbox Items, Sent Items, Outbox Items, Draft Items, Deleted Items Folder, Calendars, Contacts, Tasks, Notes, and Journals] for accessing data offline. But when there were Synchronization issues between the server and the OST file. Then the OST file gets discontinued to store data when the connection goes live. In that case, you must have an expert solution for OST file recovery and conversion.
  • An outdated version of Outlook can also be one of the reasons for the inaccessibility of OST files. Users always need to use an updated version of Microsoft Outlook in order to securely save a copy of Mailbox Outlook Items.
  • Sometimes users update their Microsoft Outlook and then open the OST file, and they find the OST file inaccessible and corrupted and cannot open the OST file.
  • When there is an Abrupt System Shutdown or there is a power failure, The OST file is corrupted and gets the error then users are unable to open the OST file.
  • Increasing OST file size is also one of the most important factors for not being accessed by Outlook and producing errors while opening OST files.

Easy Method of Fixing the OST File

If users want to open or access emails containing OST files in Outlook 2016, they need to convert the file format of the Outlook OST into a PST file, and this can be easily done by using the best converter software for OST files. There are lots of choices available over the internet, but here I would like to show you one of the most demanding software, “eSoftTools OST to PST Converter,” because this software has more powerful features to open any size of OST file in just a few seconds and gives you a full preview of every email message and other item.

This OST to PST Converter software would easily fix OST files and make them accessible through MS Outlook 2016 and all newer versions of Outlook. While using the software, you can see that this software creates a fresh Outlook PST file against your OST file and imports all emails, contacts, calendars, notes, tasks, journals, and other data into the new PST file.

A Quick Tool for OST to PST Conversion

eSoftTools developed OST to PST Converter Software is more helpful tool for those users who are facing issues like they are not able to open OST file in Outlook 2016 or 2019 and wants to view their emails by converting OST file into PST or any other formats, or they may needs to import OST mailbox data to any cloud platform. This software definitely helps those users and makes it a much easier task today. The graphical interface of this software is very clean and novice users can easily understand and operate.

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Also Read – How to Resolve Error: “Outlook Data File Has Reached Its Maximum size”?

What do you get from the software after using it?

The software has a full pack of features and gives you more than options to add OST files, preview email messages and other items, and lastly gives you more than 14+ different options to export OST files. These export options are- OST to PST, EML, EMLX, MSG, HTML, MBOX, Thunderbird, HTML, MHT, ICS, vCard, Office365, Gmail, G-Suite, YahooMail,, and IMAP Server Accounts migrations.

Here, I listed some of the special features for your reference-

  • Mail Filter: This is a great feature of the Software where users can filter the OST file emails by providing the dates range like FROM and TO date. Through this option, the software is bound to look up only those emails that are in range and then convert them into the desired file format.
  • Split Feature: This Feature is so beneficial for those who want their converted files in multiple smaller divisions, by using this feature users can split files from 1 GB to 10 GB is the range of splitting files.
  • Mail Preview: in this functionality, users can preview the Mail folders and inner content of emails with attachments. And also select the Mail folders from the OST file for conversion and recovery.
  • Naming Conventions: The naming convention is a more helpful feature for users who migrate OST files into EML, EMLX, MSG, HTML, and MHT files. The software has predefined 8+ naming convention options for users to choose and convert.
  • Support ALL Editions of Outlook OST files– The software has the latest technology-driven concept to open, scan, and convert OST files. The software has the compatibility of all editions of MS Outlook including Outlook OST 2021, 2019, 2016, 2013, 2010, 2007, and 2003 files.

Easy Steps of Converting OST into PST file format

  1. You have to download and install OST to PST Converter Software in your computer system.
  2. Open the software and click on the Select OST Button.
  3. Select the “Single file conversion” or “Bulk file conversion” option to choose the OST file.
  1. After adding the OST files, click on the “Start Scanning” button.
  1. After scanning the OST files, you have the option to check the preview of OST data and further go for the migration by clicking on the “SAVE OST” button.
  2. Now, choose the conversion options from the listing and go ahead.
  3. Provide the location where you want to save the file in your computer system and click on the “Convert” button.
  4. Now, wait for a few moments to complete the conversion process and That’s it.

After following the above-described steps, users will finally get a new PST file on their saving location. After that user can easily open the PST file in MS Outlook including Outlook 2016, 2019, and 2021.


OST files sometimes get corrupted due to several factors and cannot be accessed in Outlook 2016. Users often explore the key to solving this obstacle. However, they cannot figure out the solution. I have provided a complete Explanation of solving the issue of not opening the OST file format. Users can effortlessly open the Corrupted OST file in Outlook 2016 with the aid of this tool. This tool also provides the free Trial version, in which users can convert a maximum of 25 files from every folder of the OST file.

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