[Koha] no search results after upgrade from 17.11 to 20.11

Hi, I moved a 17.11.03 db (Debian 9) to 20.11.09 (Debian 10). I've done the following: 1) cleared cache 2) restarted memcached 3) invoked koha-zebra --restart instance 4) did a full reindex (which is showing me the correct number of records being exported. and for good measure have even restarted the box and yet "no cheese" :-( the Debian 10 box is a multi-tenant and the other instances are running correctly Any clue what I may be missing? -- Indranil Das Gupta L2C2 Technologies Phone : +91-98300-20971 WWW : http://www.l2c2.co.in Blog : http://blog.l2c2.co.in IRC : indradg on irc://irc.freenode.net Twitter : indradg