How to Fix Outlook.OST is Not an Offline Folders File Error

Outlook offers a very good facility to work offline and maintain communication on client level. Outlook allows us to work offline even in downtime of Exchange Server. But sometimes, in case of server failure or breakdown, network related issues, sudden power loss makes the ost file inaccessible and an error messages pop-ups on the system " Outlook.OST is Not an Offline Folders file ". In this blog, we are discussing about how to get rid of " Cannot open your default email folders, the Outlook .ost is not an offline folder " error.

Reasons Behind "Outlook .ost is Not an Offline Folders File Error

The main causes behind this error is corruption of OST file, corrupted OST file becomes inaccessible. Once OST file becomes corrupt, it will unable to synchronize with the server. A corrupted OST file becomes damaged in a way that Outlook cannnot recognize or sync with it. A s a result when someone tries to access or open offline .ost file, Outlook prompts an error messages "Outlook .ost is not an offline folder".

Following Fixtures Can be Applied to Fix Outlook .OST is Not an Offline Folders File

Technique 1: Run Scanost.exe/Scanpst.exe

As advised by many popular forum's sites and experts, it is advisable to use inbox repair tool to repair corrupted ost file. If you are using Outlook 2002,2003,2007 you can install and run scanost.exe (OST Integrity Checker tool ) to repair ost file and fix its error. But if you are using Outlook 2010 and later versions of Outlook you can use scanpst.exe tool to repair your OST file(it will repair corrupted PST file also).
Know in Brief about how to run Inbox Repair Tool or Scanpst.exe: https://www.ostpstsoftware.com/blogs/what-is-inbox-repair-tool.html
After completion of all required steps related to inbox repair tool, you need to restart Outlook to view and open ost file.
However, It's not a guranted solution for repairing corrupted OST file. It has been seen that the Outlook error still persists even after repairing the file.

Technique 2: Recreate OST File

Sometimes recreating OST file becomes beneficial when ost file is not able to synchronize with Exchange Server. You need to follow below steps:
1. Close Microsoft Outlook
2. Go through Control Panel and click on Mail and Profiles
3. Select the required profile
4. Select Properties and choose email address and click on change
5. Enable the "Cached Exchange Mode" under advanced settings
6. Finally press the OK to save the required changes.

Technique 3. Trendy Solution to Fix OST Error:

If you are not able to fix "OST is Not an Offline Folders File" error using the above fixtures, the best solution is to go for trusted technique, OST Recovery Software. This tool is the standalone solution to fix all types of OST errors as well as perform the following tasks.

• Repairs majorly corrupted ost file
• To recover ost file Outlook installation is not required
• Recover OST data items: emails, contacts, calendars, task etc
• Ability to repair outlook ost file by keeping secure all parts of OST email

Thus, users are suggested to go for this utility to fix "Cannot open your default email folders, the Outlook .ost is not an offline folder’ error ".