How to Safely Upgrade an Old PST File to New Outlook Version?
I have an old PST file created in an earlier version of Outlook (2003 or 2007), and I need to use it in a newer version like Outlook 2019. I am concerned about possible corruption or compatibility issues during the upgrade process. Can someone guide me through a safe and reliable method to upgrade the PST file without losing any data?

-
kevinedwards commented
If you have an old Outlook PST file that is not opening or showing errors in the new version (2016/2019/2021/365), then I can suggest you a simple tool - Softaken Upgrade PST Tool.
I have used this tool myself and it upgraded my ANSI PST file to Unicode format without any data loss.
No Outlook install required
All PST file versions supported
Simple UI, easy for non-technical users tooYou can try the free version: https://www.softaken.com/upgrade-pst-pro