The error means your MySQL module is set to use only_full_group_by mode.


The elements of the error message include:


Error Number: 1055


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


The Solution:


Disable the only_full_group_by mode.


To do so, you can either run the following SQL command:


mysql> SET sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));


... or, if you have access to the server as a root user, edit the file:


/etc/my.cnf


... by looking for the line:


sql_mode=


... and removing the value:


ONLY_FULL_GROUP_BY


... from the line.


After the file is changed, save it. Then restart your MySQL service.