OST is not a Personal Folder File is a common error that many Outlook users face. If you are looking for a reliable and quick solution to this problem then you are at the right place. In this post, we will let you know how to resolve this error in a trouble-free manner. Besides the solution, readers will also know to elaborately about how to recover corrupted ost file in Outlook.  
An Introduction to MS Outlook
MS Outlook is one of the most popular email clients in the world. Outlook is basically a desktop-based email client, but users can connect it to Exchange Server or use it as a part of Office 365 Suite. Once Outlook is configured with Exchange Server, OST file gets created. Even if the user works in the offline mode of Outlook (when it is not connected to Exchange Server,) the data gets stored in OST file. Later, the data gets synchronized with Exchange Server. Though there are many benefits of Outlook OST files, users sometimes get errors related to OST files. The error we have chosen for this post is “Outlook.ost is not a Personal Folders File.” Until the error gets fixed, users keep getting this error message. As a result, it becomes impossible for the user to continue using Outlook.
Reason Behind OST is Not a Personal Folder File Error

To solve the error, the knowledge about the cause is mandatory. Often, Outlook fails to recognize OST file or synchronize it with the Server, and that is the time when this error occurs. We have compiled some of the major reasons for Outlook.ost is not a Personal Folders File error.
  • Damaged or corrupt Outlook OST file
  • OST file not being synchronized properly with Exchange
  • Outlook getting closed suddenly because of power cut
  • OST file getting infected by malware or virus
How to Resolve OST is not a Personal Folder File Error

If we go through the reasons, it will be seen that the damaged OST file is one of the biggest reasons for the occurrence of this error. In most cases, the error gets resolved if the OST file corruption is fixed. Here we will learn how to fix OST file corruption in order to terminate “OST is not an Outlook data file” issue. Both manual method and a reliable method will be described here.
Location of OST File
Before fixing the corruption issues of Outlook OST file, let’s learn the default location of OST file in a Windows system. Going to this directory, you can find the OST file:

C:Usersuser nameAppDataLocalMicrosoftuser nameusername.ost

Manual Method to Resolve Various OST Issue
Here is the manual method that can be used to fix Outlook data file error. As all manual methods contain a high risk of data loss, users should backup OST to PST file data before performing this manual technique.

  1. Navigate to Control Panel of your system and then double-click on Mail.
  2. A dialog box will open. Click on Show Profiles option and choose the Outlook profile you use.
  3. Now select Properties option and click on Email >> Exchange.
  4. Click on Change option and select the checkbox corresponding to Use Cached Exchange Mode.
  5. Now click on More Settings>> Advanced and then click on Offline Folder File.
  6. You have to go to Settings again and click on Disable Offline>> Yes.
  7. Now, open the settings of Offline Folder File>> click OK.
  8. Click Next>> Yes.
  9. Navigate to “Cached Exchange Mode” Settings to select Use Cached Exchange Mode option. Click OK.
  10. At last, click Next>> Finish>> Close.

Shortcomings of Manual Method
The manual method we have just mentioned is not the best way to fix “.ost is not an Outlook data file.” It is a lengthy process and it is difficult to perform this technique flawlessly. Moreover, this method is not completely reliable to fix OST corruption. Due to these shortcomings, most people use OST to PST Converter.

Reliable Method to Resolve OST File Corruption
However, there is a reliable way to fix damaged OST files. There are different applications available that can resolve corruption from OST files. OST to Outlook PST Converter is an application that is highly recommended by the experts to fix “OST corruption issue” issue. The software is capable of removing OST file corruption, even the major ones. Once the OST file gets fixed, it will not show “.ost is not an Outlook data file” error anymore. This program can be used in all latest versions of Microsoft Outlook including Outlook 2016.


“OST is not a Personal Folders File” is a critical issue for the Outlook users that can cause severe trouble for them. To solve the issue, we have shared two different techniques to fix Outlook OST file corruption. Users may try any one method, but it is wise to choose the mentioned tool because of its efficiency. It will fix all types of Outlook OST file corruption and ultimately make your Outlook free of “OST is not a Personal Folders File” error.
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Diptesh Kumar Bhakat is proud to be the author of fastest growing tech blogs. He is a tech-savvy, SEO Expert, SMO Expert, SMM Specialist and a professional Blogger. Except blogging, he is so much found in photography, superbike riding. He has a very close attachment to the tech world and loves to blog on his fav topics. He has also contributed to many regional dailies and authored guest posts on some of the leading tech blogs. Professionally, he is a tech blogger and reviewer. he is a very energetic person who constantly puts up an evil smile to counter any obstacle in his manner. This dude is highly unpredictable and in reality, you can’t recognize what’s coming from him…be it his articles, generating an aura, or his personality. Mr. Diptesh is completed his B.Tech in Mechanical Engineering, as everybody thinks about one question that how a mechanical engineer can make a website?? Is it strange!!!!!!!! Yes it is. But there is a big story we will update soon.


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