Hi @jpcv222,
You can re-generate your search index by running:
php tools/rebuildSearchIndex.php
I suspect this will fix the immediate problem. But be cautious that you haven’t accidentally changed your character set configuration during the upgrade; are you having troubles with special (accented) characters? Is your config.inc.php character set configuration in the new installation the same as pre-upgrade? Is your database’s default character set UTF-8?
Regards,
Alec Smecher
Public Knowledge Project Team