I recently installed MythTV using the Mythbuntu 16.04 distribution. All went well until I tried to use MythWeb, where the web browser displayed this error:
datetime: 2016-07-18 21:20:19 (BST) errornum: 256 error type: User Error error string: !!NoTrans: SQL Error: Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'mythconverg.recordedmarkup.data' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by [#1055]!! filename: /usr/share/mythtv/mythweb/classes/Database/Query/mysqlicompat.php error line: 98
Fortunately I found the solution at https://code.mythtv.org/trac/ticket/12713 . I edited /etc/mysql/conf.d/mythtv.cnf from:
[mysqld] bind-address=:: max_connections=100 sql_mode=NO_ENGINE_SUBSTITUTION
and rebooted. Thankfully this solved the problem.