Yesterday, I had encountered the same problem in Outlook 2016 without any prior notice. Then, I took the assistance of ScanPST.exe to eliminate this error. But, it failed repeatedly before scanning entire Outlook data file.
I also went through ScanPST.exe alternatives but no one is freeware. Till now, I have collected some useful references:
Top 6 Best PST File Repair Tools for all MS Outlook Versions
Five reliable Outlook PST file repair tools - TechRepublic
https://www.stellarinfo.com/outlook-pst-file-recovery.php
But, the above references are talking about paid tools. If possible, help me to find any freeware.