I was trying to upgrade my old Outlook PST files to newer Outlook versions, but kept getting errors, and the file wouldn't open. I tried several manual tricks but couldn't succeed. Then I discovered Softaken PST Upgrade Software. Using this tool, I easily converted my old ANSI PST files to Unicode PST files. The best part is that there was no data loss, and all my emails, contacts, calendars, and attachments remained safe. This software supports all Outlook versions, and the process is quite easy. Try using this tool if you're having problems with PST upgrades as well.