Mysql2::Error: Incorrect string value

Question

the problem is caused by charset of your mysql server side. You can config manually like:

ALTER TABLE your_database_name.your_table CONVERT TO CHARACTER SET utf8

or drop the table and recreate it like:

rake db:drop
rake db:create
rake db:migrate

references:

https://stackoverflow.com/a/18498210/2034097

https://stackoverflow.com/a/16934647/2034097

UPDATE

the first command only affect specified table, if you want to change all the tables in a database, you can do like

ALTER DATABASE databasename CHARACTER SET utf8 COLLATE utf8_general_ci;

reference:

https://stackoverflow.com/a/6115705/2034097