This guide will teach you how to fix the error Mysql2::Error: Unknown column. We are going to use an example for the Agile plugin.
Note: But the fix should work for all other kinds of errors with this type no matter the plugin.
Description of the problem
So, the error in our case for the Agile plugin is:
FATAL -- : ActionView::Template::Error (Mysql2::Error: Unknown column 'agile_data.agile_sprint_id' in 'on clause'):
Solution
Please delete the agile_data table in the MySQL server and then rerun the installation commands, it should fix your problem.