OST File Not Recognized by Outlook 2019, 2016, 2013 & 2010 – What to do?

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  • Published on
    January 18th, 2020
  • Updated on
    February 2, 2021
  • Read Time
    5 minutes
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Today with this blog we are going to discuss one of the most common error of MS Outlook i.e. “OST File Not Recognized by Outlook”. Here we cover the reasons of it occurrence, various solutions and then the expert choice.

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Let’s take it from the core, MS Outlook is one of the most popular email client preferred by various organizations as a medium of communication. The Outlook has always been users’ first choice because of its smart and proactive features.  MS Outlook can be work with Exchange Server and SharePoint Server, when it collaborate with Exchange server it creates OST files.

OST file is an offline folder and makes it possible for us to work in offline mode or in slow internet connectivity. Later, once the connection with Exchange server establishes, this OST file is automatically updated in the user’s Exchange account. But sometimes this OST files may get corrupted and throws unexpected errors like “OST File Not Recognized by Outlook”.

In such conditions, users get panic to find the proper solution as this error can cause to the data loss. But, before checking for the solution let’s see the real cause of this error.

Causes of OST File Error

OST File Corruption – OST files are prone to corruption that’s why it can be corrupted due to any reasons like virus attack, reaching to the file size limitation etc. thus leads to this abnormal error.

OST File Synchronization – if your OST files unable to synchronize with Exchange server due to any reason then Outlook report this error.

Manual Solution to Fix Outlook does not Recognize OST File Error

Method 1 – Recreate OST File

Note – Following these steps you can create the OST file of any email account.

Step 1: Go to Control Panel and click on the Mail button.

Step 2: In Mail Setup, click on Show Profiles, select your profile and choose Properties.

Step 3: On E-mail tab select Exchange account, click on the Change button and enable Use Cached Exchange Mode.

Step 4: Go to More Settings. In the Advanced tab, choose Offline Folder File Settings.

Step 5: Now choose Disable Offline Use option and then, click on “Yes” button.

Step 6: Go to Offline Folder File Settings, select OK and Yes button.

Step 7: Now choose the checkbox Use Cached Exchange Mode.

Step 8: Click on the OK button, go Next and Finish.

Step 9: Close the Account Settings and Mail Setup wizard.

Method 2 – Inbox Repair Utility

Inbox repair utility is the inbuilt tool of MS Outlook to diagnose the issue, now follow these methods to fix the OST file is not recognized by Outlook error.

Step 1: Launch the inbox repair utility

Step2: Click on the Browse button to select the OST file

Step3: Press the Start button and scanning process will start

Step4: After the scanning it will generate a list of errors. Then, choose the Repair button

Step5: Now restart Outlook and check if the OST file works or not.

Method 3 – Expert Choice to Solve Error OST File Not Recognized by Outlook

After implementing above two methods, still you are unable to access OST file and getting the same error message of Outlook does not recognized OST file, then you must go for professional approach. As mention above two methods are not sure shot solution to solve this OST file error, so we suggest you to try OST to PST converter. This software is exclusively designed to convert OST files into PST format along with all the email items. Also this program will repair your damaged OST file with in second and let you access all the important emails, contacts, calendar etc. This handy converter is compatible with all the versions of Windows 10 and MS Outlook 2019, 2016, 2013, 2010 etc.

Follow the steps to fix OST file Not Recognize Error with SysInfoTools

Step1: Launch the OST to PST Converter; select the corrupted OST file by clicking on browse button

Step2: Choose the scanning option (Standard, Advance, & Deep)& click ok button

Step 3: Once the scanning is done, check the preview

Step 4: Choose the folder and click on save button

Step 5: As you click on save button conversion gets started.

Step6: Now import this converted PST file in your outlook and check your emails.


Now you know your answer what to do if OST file does not recognized error prompt in your computer screen. The most common reason of any Outlook error is the file corruption and it can be happen anytime without your knowledge. Hence it is always requested to manage your data files very carefully as these are filled with loads of vital information. We have talked about all the possible solutions (manual or automated) to resolve this issue. If you want to know about top 5 OST to PST converter then read here. You can opt any of them. Hope you like this article! Please share your views in the comment section.

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