By Eric Simson
Though Outlook OST (Offline Storage Table) files are closely related to Exchange mailbox, they are an independent entity. This means that although OST files mirror the data present in the user mailbox on Exchange server, any change of status or damage in the server does not affect OST files. This is what makes them so useful. In the event of server downtime, because of OST files, users can continue working on their mailbox data without any interruptions. And when the server comes back online, all modifications made to the mailbox data locally (through OSTs) is merged automatically with the actual mailbox on the server.
The above explanation clearly points out the robustness and reliability of OST files. However, there are situations wherein OST files tend to fail. Such situations involve damage and corruption to OST which is in fact, not very uncommon. This discussion focuses on an oft seen error message that users face when dealing with OST files –“Errors have been detected in the file xxx.ost”. We’ll also be pointing out solutions for Outlook error fix towards the end.
The error and the reasons behind it
On trying to launch MS Outlook, appearance of the following error pop-up indicates corruption in the OST file:
Error has been detected in the file xxxx.ost. Quit Outlook and all mail-enabled applications, and then use the inbox repair tool (Scanpst.exe) to diagnose and repair error in the file.
Before moving to the fixes for this error, let’s cast a brief glance over the primary reasons that trigger its occurrence:
• Sudden termination of Outlook while Outlook-Exchange synchronization is in progress
• Abrupt system shutdown while Outlook-Exchange synchronization is in progress
• File system corruption
• Virus infection to the OST
How to repair OST file
There are several ways to repair OST file and apply Outlook error fix:
1. Restore from backup
The best way is to replace the corrupted OST with a backed up copy.
However, this method suffers from a limitation. If the backup was not taken very recently, using this method could leave you with missing data that was modified after the backup was taken.
2. Repair OST using inbuilt Inbox repair utility
Microsoft offers two inbuilt utilities to repair issues with Outlook data files. Named ScanPST.exe and ScanOST.exe, these utilities can be used to fix minor issues within PST and OST files respectively.
This method too comes with drawbacks. The ScanOST.exe utility cannot fix severe corruption issues within OST. Also, this utility is not available in Outlook versions beyond 2007. So if you’re using Outlook 2010, 2013 or 2016, this utility won’t be available.
3. Clear all offline data within OST file and recreate it
Purging the OST of all offline data could eradicate the cause of corruption within it. Hence, try clearing the OST as follows:
a. Locate the OST file on your machine.
b. Right click on the folder containing the file and select properties.
c. In the dialog box that opens, choose the option "Clear Offline Items"
d. Click OK.
e. Launch Outlook
f. Click the Send/Receive tab from the Outlook 2010 ribbon. After that click "Update Folder"
After following the above steps, delete the OST file. Now when Outlook synchronizes with Exchange, a new OST will automatically be created and all data within the Exchange mailbox will be downloaded into it.
This method though very effective might leave you with slight data loss if the OST corrupted before the recent changes were merged with Exchange mailbox. Moreover, this is not a guaranteed method of repairing OST file.
4. Create a new Outlook profile
In rare cases, the cause behind this error could be corruption of your default Outlook profile. In such a case, follow the below mentioned steps to create a new default Outlook profile:
a. Deleting the current default Outlook profile
b. Create a new profile
c. Set the newly created profile as the default one
In case this method too is unable to resolve the issue, the only option you might be left with is converting OST to PST using third-party tool.
5. Convert OST to PST using third-party tool
If none of the above methods work, the most recommended way to fix the error would be to convert OST to PST using trusty third-party tool Stellar OST to PST Converter. This competent application extracts all objects within corrupted OST and converts them into PST format. The converted PST can then be directly imported into Outlook to access all data. Here are the steps to use this tool:
a. Download, install and launch Stellar OST to PST Converter
b. On the main software screen, select or find the corrupted OST file
c. Click on Start to start the scanning process
d. See the progress of the scan. You can stop it at any time through a convenient Stop button
e. After the scanning completes or is terminated, all recovered items are listed in a tree-view list in the left hand panel of the software screen. Here, you can double-click on any item to preview it before recovery.
f. Now to actually recover data, click on Save Converted File in the main menu.
g. Select the target format in which you wish to save the converted data (available options are PST, MSG, EML, RTF, HTML and PDF
h. Browse to select the desired location where you wish to save the data
i. Click OK to complete the process
Hope one of the above mentioned methods are able to fix the error. If none of the free methods work, don’t hesitate to use the commercial software Stellar OST to PST Converter to safely and accurately convert all OST data to PST format.