Configuring a POP3 account in Microsft Outlook creates a local .pst file for all its core functionality like storing email messages, calendars, contacts, and more. However, PST files can be prone to several issues compromising your outlook functionality, data, and security concerns.
Read the upcoming section as it addresses all the common Outlook PST file issues, causes, and the DIY solutions to fix them.
Common Outlook PST Issues and Their Solutions
- PST File Corruption or Damage
- PST File cannot be Found
- Unable to Copy Outlook PST File
- PST Sync Issues
- Cannot Open PST File
- Large PST Files
- Remove Password from PST file
- Outlook.pst is Not Compatible
- Deleted PST Files
1: PST File Corruption or Damage
PST corruption is one of the common issues in Outlook that prevents you from accessing the data within the PST file or causes Outlook crashes. It can be caused by sudden shutdowns, virus or malware attacks, or hard disk failures.
Fix 1: Inbox Repair Tool
You can locate the built-in PST repair tool, Microsoft Outlook ScanPST, to fix corrupt or damaged PST files or use third-party PST repair tools that can repair PST files.
Fix 2: Restore From Backup
If you have a recent PST file backup, restore it to bring back your PST data.
Fix 3: Verify the Disk health
If bad sectors in your hard drive are causing the PST file corruption, then run the chkdsk command to fix errors in your drive, here is how you do it:
- Open Command prompt as Administrator.
- Type chkdsk X /f /r (Replace X with your drive letter) and press Enter
Wait till the scan is completed, restart your device, and try accessing the PST files.
Can You Fix a Corrupt PST File?
Yes, a corrupt PST file can often be repaired, in most cases you do not need to lose any data in the process. Microsoft provides a built-in utility called ScanPST.exe (also known as the Inbox Repair Tool) that scans the internal structure of a PST file, identifies logical errors, and rebuilds damaged headers, folders, or indexes. It is free, ships with every version of Outlook, and handles mild to moderate corruption reliably.
To run ScanPST.exe, close Outlook completely, then navigate to its install location. On Outlook 2019 and Microsoft 365, the typical path is C:\Program Files\Microsoft Office\root\Office16\SCANPST.EXE. Open the tool, click Browse to select your PST file, then click Start. Once the scan completes, check the Make a backup of scanned file before repairing option and click Repair. The tool may need to be run multiple times on severely damaged files before corruption is fully resolved.
For PST files that are too heavily damaged for ScanPST to handle like missing data blocks, zero-byte files, or files that fail every repair attempt, a third-party PST repair tool like Rikvr PST Repair software is the next best option.
2: PST File cannot be Found
You could run into an “Outlook data file cannot be found” error if the PST file is moved, renamed from the default PST file location, or corrupted. In these cases, you won’t be able to access your messages, events, and contacts directly through Outlook.
Fix 1: Manual Search
Manually locate the PST file using the Outlook application. Here is how you do it.
- Launch Outlook, Go to File > Account Settings > Account Settings.
- Select the data files tab to see the location of your PST file.
Fix 2: Repair PST File
Use the inbox repair tool by Microsoft to repair the damaged .pst files, locate the ScanPST tool, and run the tool to get rid of the “Outlook.pst cannot be found” error.
3: Unable to Copy Outlook PST File
There are a few reasons why the Outlook PST file won’t copy, it can be due to Outlook file lock, permission issues, or a large PST file that is preventing you from copying the Outlook PST files.
Fix 1: Check File Permissions
Check the file permission of the PSt file that you are trying to copy, and ensure that you have the permissions to copy and write on both source and destination folders.
Simply right-click the PST file and folders, choose Properties, go to Security, and check the permissions.
Fix 2: Check Outlook and Related programs
Opening the Outlook application prevents from PST files being copied from one location to another so make sure that you have closed Outlook and the related applications while copying the PST file.
Fix 3: Verify the File size
If you are trying to copy a large, consider splitting the PST file into smaller chunks and try copying them.
4: PST Sync Issues
When the Outlook PST file doesn’t sync and reflects improper data, it could be due to an Outlook file lock, an outdated Outlook application, or conflicting add-ins.
Fix 1: Close Outlook and Restart
Ensure the network connection on your device and close and relaunch the Outlook application to remove temporary glitches causing the sync issue.
Fix 2: Disable Add-ins
Temporarily disable the add-ins, relaunch the Outlook, and verify if the add-ins are causing Outlook .pst sync issues.
Fix 3: Update Outlook application
Ensure you use an updated Outlook version, as updates often include bug fixes and performance improvements that can prevent PST syncing issues.
5: Cannot Open PST File
When you cannot open the PST file you will run into “Outlook . PST cannot be Opened” caused when your PST file backup running in the background, any other software conflicting with Outlook, etc
Fix 1: Close All Processes and Programs
Ensure no Outlook instances are running in the background. Use Task Manager to terminate any Outlook-related processes.
Fix 2: Disable Outlook Compatibility Mode
Disable compatibility mode on Outlook to ensure that Outlook runs on the latest system resources and settings to increase the performance and ability to access the PST files. Here is how you do it:
Right-click the Outlook shortcut, select Properties, and uncheck Run this program in compatibility mode.
Fix 3: Fix the PST file
If your PST file has minor corruption issues, then you can repair the PST files using inbox repair too For severe corruption issues try using a professional Outlook repair tool to fix the corrupt PST files.
Can a PST File Be Too Big? Size Limits by Outlook Version
Yes, PST files have hard size limits that vary by Outlook version, and exceeding them is one of the most frequently overlooked causes of data loss and corruption. When a PST file reaches its maximum capacity, Outlook can no longer write new data to it. This causes emails to silently fail to save, calendar entries to disappear, or in worst-case scenarios, the entire file to become unreadable.
The table below outlines the official PST size limits across major Outlook versions so you can assess whether file size is contributing to the common PST file issues you are experiencing:
- Outlook 97–2002 (ANSI format): Maximum size of 2 GB. Exceeding this limit is known to cause irreversible corruption.
- Outlook 2003–2007 (Unicode format): Default limit of 20 GB, with a configurable registry cap up to 50 GB.
- Outlook 2010 (Unicode format): Default limit of 50 GB, configurable up to 2 TB via registry.
- Outlook 2013, 2016, 2019, and Microsoft 365: Default limit of 50 GB, with registry modifications allowing files up to 2 TB in size.
If your PST file is approaching these thresholds, the recommended fix is to archive older items into a separate PST file using Outlook’s built-in AutoArchive feature, or to use a PST split tool to divide the oversized file into smaller, more manageable chunks. Staying below 80% of the version-specific limit is considered best practice to prevent performance degradation and accidental data corruption caused by size overflow.
6: Large PST Files
If you have emails with large attachments, junk mail, or any calendar data can result in a large PST file. Here is how to fix it.
Fix 1: Use the Cleanup Tool
You can use Outlook’s built-in cleanup tool to remove unnecessary emails and duplicates, reducing clutter and lowering the PST file size.
- Click on File >Tools > Expand drop-down next to Mailbox settings.
Choose options and delete the following from your Outlook
- Clean Up Conversation: Removes redundant messages within a conversation.
- Clean Up Folder: Erases unnecessary messages based on certain criteria.
- Clean Up Folder & Subfolders: Applies the cleanup to the selected folder and its subfolders.
Fix 2: Archive old Mails
You can archive all your old emails to a separate PST file to free up space in the primary inbox and manage large PST files effectively.
- File > Tools > Set Archive folder and choose the folders to archive.
- Choose a location for the archived items (either a new PST file or an existing one.) and click on to initiate the archiving process.
7: Remove Password from PST File
Most users encrypt the PST file to prevent unauthorized access and sharing and tend to forget the password which prevents them from accessing the Outlook data. Try the solutions listed below to remove the .pst file password
Fix 1: Remove Password via Data File Settings (if you remember the password)
- Go to File and Account Settings click on Account Settings open the Data Files tab.
- Choose the PST file you want to remove the password from and click on Settings.
- Choose Change Password and enter the current password.
- Leave the New password and Verify password fields empty and click on OK to remove the password.
Fix 2: Use Password Recovery Tools (if you don’t remember the password)
If you have forgotten the password then you will have to use a third-party password recovery tool to remove the password from your PST files. Ensure that you choose the tools with caution, as there is a risk of corruption or data loss.
8: Outlook.pst is Not Compatible
If the PST file is of a different version of Outlook or from a different OS it can cause the “Outlook.pst Is Not Compatible” which prevents accessing their data. It can PST files can be corrupted or unsupported file format.
Fix 1: Repair Outlook Installation
You can repair the using the built-in repair tool, here is how you do it:
Control Panel > Programs and Features > Right-click on the Office suite > Change and choose Quick Repair.
Fix 2: Create a New PST File
You can create a PST file that is compatible with the Outlook version that you currently use, and manually transfer all the necessary data from the old PST file.
9: Deleted PST Files
When you have deleted or lost PST files from Outlook, you will have to choose the proper recovery solutions to bring back the PST files depending on how you lost it
Fix 1: Check Recycle Bin
Verify if the deleted or lost PST file is present in the Recycle Bin. If yes, then simply restore the PST file from the Recycle Bin.
Fix 2: Check for Backup
If you have enabled File History or have any recent backup of the PST file, you can restore the PST file from there.
Fix 3: Choose a Data Recovery Software
If you can’t recover the deleted PST file from any of the above solutions, use specialized data recovery software to attempt PST recovery. Make sure you choose a reliable tool that lets you download and scan for free.
Frequently Asked Questions About Common PST File Issues
What causes PST file corruption in Outlook?
PST file corruption is most commonly caused by abrupt system shutdowns while Outlook is writing data, hard disk bad sectors, malware or virus infections targeting mail storage files, PST files exceeding their version-specific size limits, and network interruptions when a PST is stored on a mapped or shared network drive. Using a PST file stored on a network location rather than a local drive significantly increases the risk of corruption and is explicitly discouraged by Microsoft.
How do I repair a PST file without ScanPST?
If ScanPST.exe fails to repair your PST file — which can happen when the file header is completely destroyed or when the file is a zero-byte placeholder — you have two main alternatives. First, restore the file from a recent backup if one exists. Second, use a reputable third-party PST repair tool that can perform deep-level binary analysis of the file structure and recover individual items such as emails, contacts, and calendar entries even from heavily damaged PST containers. Always verify tool credibility by checking for a free trial with data preview before purchase.
What are the main limitations of PST files?
The key limitations of PST files include strict size caps that vary by Outlook version (as low as 2 GB in older ANSI-format files), single-device accessibility since PST files cannot be reliably shared across multiple computers simultaneously, vulnerability to corruption from power failures or bad disk sectors, no automatic cloud backup unless explicitly configured, and weak security in legacy formats that lack modern encryption standards. For organizations requiring reliable multi-device access and data redundancy, Microsoft Exchange or Microsoft 365 cloud mailboxes are strongly preferred over local PST storage.
Are PST files still used in Outlook 365?
Yes, PST files can still be created and used in Microsoft 365 (formerly Office 365), but they are no longer the default or recommended storage method for Microsoft 365 accounts, which use OST files synced to Exchange Online. PST files in Outlook 365 are typically used for local archiving of old messages or for importing mailbox data from legacy accounts. Microsoft has actively discouraged PST use in enterprise environments since Outlook 2013 and offers the Microsoft 365 compliance center as the preferred archiving solution.
Preventative Measures to avoid Outlook PST issues
Here are some key preventative measures you can take to avoid PST file issues in Outlook
- Backup Outlook PST file: Create regular backups of the PST Files in an external drive or cloud storage to ensure that you have a PST file that is safe even if the original file is corrupted or lost.
- Delete Unnecessary Emails: Delete unwanted emails from the inbox to reduce clutter and PST file size.
- Verify the add-ins: Review the third-party add-ins in your Outlook application, and disable them if you are not using them as few add-ins might store data in the PST file.
- Compact PST File (Periodically): Use the Compact Now function to remove unnecessary data helping in reducing the PST file size.
Conclusion
We hope the solutions listed in this help address all the common PST issues that stop you from accessing Outlook data and functionality.
Additionally implementing the above preventative measures can significantly reduce the risk of PST file issues and ensure optimal performance for your Outlook.
