Corrupt PST File – 5 Most Common Reasons You Should Know

An Outlook data file is one of the most valuable things for any Outlook user. Any mishap that takes place with this file can truly be a nightmare. For a computer user, there is nothing so bad as corruption. If it takes place due to any reason, you may lose your important data. Almost all computer files are prone to corruption, and an Outlook data file is no exception. There are many reasons which can cause corruption in the Outlook data file. In this article, we will be covering the most common reasons behind a corrupt PST file.

Have you ever faced corruption in your Outlook data file? How do you come to know that a file has been corrupted? Before discussing all these things, let us get familiar with Outlook data file.

PST – Personal Storage Table

Microsoft Outlook is an email client application that has more additional features than any other email client in the market. Other than email, it includes a contact manager, calendar, task manager, note-taking, journal, and a web browser. Microsoft Outlook stores all the emails and other data into an Outlook data file. This Outlook data file is commonly known as PST (personal storage table). It is created on the local computer where the Outlook client has been installed. This is a little about a PST file. To learn more about the PST file, you can visit Personal Storage Table. Now let us discuss how a PST file gets corrupted.

Corrupt PST File

Outlook users often face error messages while using Microsoft Outlook if there is an issue with the Outlook data file. How many times have you come across an error message while working on a PST file? Have you ever tried to find out why an error pops up from nowhere? Let us suppose you receive this error message, “The file is not an Outlook data file (.pst).”


corrupt PST file error message


The error says that the file you are trying to open is not an Outlook data file (.pst). This might be frustrating because you know the file you are trying to open is a PST file. When it is a PST file, why is Outlook showing this error? If this is your question, I have the answer. You are getting the above error just because the PST file you are trying to open is corrupted. Yeah, you heard it correct! The PST file is corrupted, and that is why Outlook fails to recognize it. 

Common Error Messages

There are so many error messages that you may come across if a PST file is corrupted. Below is a list of the most common error messages:


  • The file is not a personal folder file.
  • Errors have been detected in the PST file.
  • An unexpected error prevented access to this file. Use ScanDisk to check the disk for errors, and then try using the Inbox Repair tool again.
  • Unable to display the folder. The PST file could not be accessed.

Microsoft provides a built-in repair utility to repair PST file, it is called scanpst. You can run this application to scan the corrupt PST file. Many times, scanpst utility works successfully. But it may fail to repair PST file in a case of severe corruption. In such a situation, you may come across any of these error messages:


  • The Inbox Repair Tool does not recognize the file.
  • The PST file fixed by Inbox Repair Tool (Scanpst) is empty or does not contain the wanted items.
  • Inbox Repair Tool (Scanpst.exe) hangs endlessly and does not perform the repair.
  • Scanpst reports “Fatal Error 80040818” when trying to repair the PST file.
  • Scanpst reports “An unknown error prevented access to the file. Error 0x80070570: The file or directory is corrupt and unreadable”.

Now you must be wondering the reasons that can corrupt PST file. 

Common Reasons for Corrupt PST File

Just like any other computer file, an Outlook data file is also not immune to corruption. There are various reasons that lead to frequent PST file corruption. Below are the most common ones:

PST Becomes Oversized

It is one of the most common reasons leading PST file corruption. An Outlook data file has a size limit issue. There is a maximum size for both ANSI and Unicode PST files. Whenever a PST file reaches its maximum size or crosses it, it becomes inaccessible. Please keep in mind that an oversized PST file is highly prone to corruption.


Useful Tip: Make sure a PST file never reaches its maximum size. There are so many things you can do to manage an oversized PST file, such as compress PST file size, split PST file, remove duplicate items to get more free size in the PST file.

Virus Infection

A computer virus can infect any file and make it corrupt with ease. Generally, computer viruses can harm your computer files by overwriting, deleting some parts of the files, adding junk characters to them, etc. An Outlook data file is not immune to virus infection if you are not using Antivirus software.


Useful Tip: Make sure you are using an updated Antivirus software, and do not forget to scan your computer regularly. Also, never open and download attachments sent from an unknown sender.

Power Failure

If a computer shuts down abruptly, this may put all your data at high risk. Since operating systems are very complex, they need to go through a proper shutdown process in order to make sure that all the running processes have successfully closed before shutting down. For instance, you are working on a PST file in Microsoft Outlook. Suddenly, your computer shuts down abruptly due to power failure. The next time you try to open the file, it is corrupt.


Useful Tip: The best way to overcome power failure issues is by using the UPS device. It gives you power back during frequent power outages. Also, keep in mind that you should never close any software program and the computer system forcefully.

Faulty Network Devices

Sometimes if the network devices are faulty, it may lead to PST file corruption. The network devices include network interface cards, cables, routers, hubs, etc. Let us suppose you store the Outlook data files on the network server. You try to open them on a client computer via network links. If there is any problem in any of the network devices, this remote access process can make the PST file corrupted.


Useful Tip: Never use faulty network devices. Do not forget to perform regular maintenance of your network.

Software Malfunction

Almost every computer program has deficiencies, and Microsoft Outlook is no exception. Software malfunction refers to a state when a computer program starts producing incorrect or unexpected results. This may happen due to many reasons which include viruses and software collisions. Microsoft Outlook can collide with any other computer program. This action may make a bad impact on PST files directly and make them corrupted.


Useful Tip: There are various things you should do to prevent software malfunction. Never use pirated software and never download software from an unauthorized source. Use updated antivirus software, and do not forget to scan your computer regularly.


In this article, we have explored the most common factors for PST file corruption. Also, we have discussed the most common error messages which occur due to corrupt PST file. Every Microsoft Outlook user should aware of the reasons so they can avoid corruption before it occurs. Unfortunately, if corruption occurs, you should try to repair PST file by using scanpst utility. For better results, you should consider using a professional PST Recovery software.