If the PST splitting process fails midway while using DataVare Outlook PST Split Expert, its usually due to issues like file corruption, insufficient system resources, or access conflicts. To resolve this, first make sure the PST file isn't broken. Use Outlook's built-in ScanPST (Inbox Repair Tool) to fix any problems. Next, make sure Outlook is entirely closed and that no other programs are using the PST at the same time, as this can stop the operation. Make sure the destination drive has adequate free disc space, because not having enough space can cause the procedure to fail in the middle. Also, to avoid permission problems, run the PST Split Expert utility as an administrator. If your PST files are particularly big, you could be interested in breaking them into smaller target sizes to make them easier to handle. Following these steps will make sure that the splitting process goes successfully and that no data is lost and the folder structure stays intact.