When you use Microsoft Outlook to open a corrupt or orphaned offline folder (OST) file, or synchronize it with the Exchange server, you will encounter various error messages, which may be a bit confusing to you. Therefore, here we will try to list all possible errors, sorted according to their occurring frequency. For each error, we will describe its symptom, explain its precise reason and give out the solution, so that you can understand them better. Below we will use ‘filename.ost’ to express your erroneous Exchange OST file name.
- “Cannot open your default email folders. The file xxxx.ost is not an offline folder file.“
- “Unable to expand the folder. The set of folders could not be opened. Errors could have been detected in the file xxxx.ost. Quit all mail-enabled applications, and then use the Inbox Repair Tool.“
- Encounter a large numbers of conflict items.
- Cannot open particular Outlook items when offline.
- Various errors when synchronizing Exchange Server mailbox with your OST file.
Moreover, when using offline folder (OST) file with Microsoft Exchange server, you may also encounter the following problems frequently, which can be solved by DataNumen Exchange Recovery easily.