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Summary: Microsoft Outlook, a versatile email client, uses PST and OST files for mailboxes. OST issues due to corruption or size can be fixed using built-in tools. Renaming and recreating the OST file may help. For thorough recovery, consider Kernel for OST to PST Converter.

Microsoft Outlook serves as a versatile email client compatible with numerous platforms and boasting robust support for a wide range of email servers. To accommodate varying user needs, Outlook generates distinct data files to manage user mailboxes. When connected to POP servers, it generates PST data files, while for IMAP, Exchange, and Office 365, it produces data files in the OST format. Relocating PST files is a relatively straightforward process, whereas OST files are more intricately tied to the email server, making OST file management more complex compared to PST files.

At times, when an Outlook user attempts to access the OST file from its original location, they may encounter difficulties in locating the file and receive an error message stating:-

‘Not a valid path. Outlook cannot find OST file.’

Users might find it surprising that Outlook does not display any errors regarding the absence of the OST file until they intentionally attempt to access it. However, several underlying reasons can contribute to this error, and a few of them are outlined below:

A corrupt OST file

The OST file could have become corrupted, rendering it inaccessible to the Outlook application. This could be the underlying reason why the application is unable to locate it.

Large-sized OST file

It is recommended to keep the size of the OST file to a manageable size, and when the OST file oversized, then Outlook will have to take more effort in loading the file. Sometimes, Outlook cannot load the file and show the error that it did not find the OST file.

The hard-drive sector has crashed

If the sector of the hard drive where the OST file was saved becomes corrupt, then Outlook will not find it and show you the error. Now the OST file will be inaccessible and you cannot perform the basic operation like change the location of OST file, searching the mailbox data, or accessing it.

Sudden power failure

In the event of a power failure occurring during the synchronization of the OST file with the Exchange Server, corruption becomes inevitable. Such a situation can potentially lead to the corruption of not only the OST file but also the entire Outlook application.

Manual methods to repair the corrupt OST files

When Outlook begins displaying the message “Microsoft Outlook unable to locate the OST file,” you can employ all the available methods to initiate the repair process.

For Outlook 2007, 2003

For the older versions of Outlook, the user can opt to use the inbuilt ScanOST tool to check and integrity and health of the OST file.

  1. First, close Outlook and its associated applications.
  2. Open ScanOST tool from its location – C:\program files\common files\System\Mapi\LocaleID\scanost.exe
  3. Open the application and click OK to scan all the OST files that you have chosen to scan.
  4. Use the Repair Errors checkbox, and then click the Begin Scan button to proceed with the process.

Starting from Outlook 2010, the ScanOST tool has been replaced by the ScanPST tool, and it can be utilized in a similar manner to repair OST files. However, it’s worth noting that the built-in tool may not effectively handle cases of severe corruption, and an OST file that is seriously damaged may be irreparable using this tool.

You can recreate the OST file containing the complete data replacing the irrecoverably damaged OST file. Use the steps below:

  1. Close the Outlook application completely.
  2. In Control Panel, click Mail (Microsoft Outlook 2016).
  3. Control Panel

  4. Click the Email Accounts option.
  5. Email Accounts

  6. Choose the Exchange Account which has an inaccessible OST file, and click the Change button.
  7. Choose the Exchange Account

  8. Click the More Settings button.
  9. More Settings

  10. Go to the Advanced tab, and make sure to check the option to Use Cached Exchange Mode.
  11. Use Cached Exchange Mode

  12. Click the Apply button.

You can resolve the issue by navigating to the OST file location, renaming it, and then restarting the Outlook application. Upon restart, Outlook will create a new OST file that should be in a healthy and accessible state.

Final words

The OST file is the Outlook data file that stores user data when using the Exchange Server in offline mode. Since it can contain crucial professional data that you wouldn’t want to lose, you have two options for recovering OST file data: manual methods or using an OST to PST file conversion tool. One such tool is the Kernel for OST to PST Converter, which is capable of removing corruption from any OST file and repairing it. This tool offers several advanced features to preserve the quality of OST data and provides full control over converting it into a PST file.

Kernel for OST to PST