Elements of the error message include:

Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column

this is incompatible with sql_mode=only_full_group_by

Filename: libraries/Datamapper.php(1) : eval()'d code(3) : eval()'d code

Line Number: 1348


Your server MySQL module is set to use "only_full_group_by" mode.


The quickest fix would be to disable the "only_full_group_by" mode.

Where you have access to the server as root user, edit:

/etc/mysql/my.cnf file.

Look for the "sql_mode=..." line and remove the ONLY_FULL_GROUP_BY value from the line.

After the file is changed save it.  Then restart MySQL service ( service mysql restart )