activerecord - In rails, how can I find out what caused a .save() to fail, other than validation errors?

Question

I have an ActiveRecord model which is returning true from valid? (and .errors is empty), but is returning false from save(). If the model instance is valid, how can I find out what's causing the save to fail?

Answer 1

If @user.save (for example) returns false, then just run this to get all the errors:

@user.errors.full_messages