Microsoft Outlook OST file may get corrupt due to different reasons, such as the crash of MS Exchange Server, corruption of MS Exchange database, virus infection, failure of the hard disk drive, sudden system shut down, abrupt handling of MS Outlook, and more. Whatever the reason is behind the damage of the OST file, you will see the below error message when you will try to access its data from your Outlook account:
"Unable to expand the folder. The set of folders could not be opened. Errors could have been detected in the file xyz.ost. Quit all mail-enabled applications, and then use the Inbox Repair tool."
In the above error message, xyz.ost is the name of the OST file associated with your Outlook profile.
After looking at the aforementioned error, you may think that everything stored in the OST has been lost. If this is the case, do not worry because here you will know the process to fix the corrupt OST file / resolve the aforementioned error message. Follow the steps given below:
In case, these steps do not resolve the "Unable to Expand...." OST file Synchronization Error, then you will have to repair the OST file and convert it into a PST file using an advanced OST to PST converter. Once you have a good OST to PST Converter installed in your computer, perform the below steps:
This way you can resolve the "Unable to Expand...." OST file Synchronization Error.