I just upgraded from v16 to v18. Data folder and config.php file were not overwritten.
When I finished the upgrade, everything seem fine, but when I login to machform panel and load the entries, it shows emtpy, nothing show up. Then I login to cpanel and check my sql database, all the data is still there, and I test a new submission, and the new data can write into sql database accordingly.
So it seems to me that it is just the manage_entries.php doesn't do the job?