ActiveRecord SerializationTypeMismatch MySQL SQLite

I was having this error in Development but not in Test:

ActiveRecord::SerializationTypeMismatch: cambiable_attributes was
supposed to be a Hash, but was a String

Which was the problem?
I was using MySQL in Development and SQLite3 in Test. Field
'cambiable_attributes' was type String in the DB schema and had to be
type Text.
I changed the data type to Text and it worked well in both environments.