ArgumentError: Unknown key: :order. Valid keys are: :class_name, :anonymous_class in Rails 4.2.6
<p>I am getting the following error while running rake db:migrate:</p>

<blockquote>
  <p>ArgumentError: Unknown key: :order. Valid keys are: :class_name,
  :anonymous_class, :foreign_key, :validate, :autosave, :table_name,
  :before_add, :after_add, :before_remove, :after_remove, :extend,
  :primary_key, :dependent, :as, :through, :source, :source_type,
  :inverse_of, :counter_cache, :join_table, :foreign_type</p>
</blockquote>

<p>This is the model where I am getting error:</p>

<pre><code>class Report &lt; ActiveRecord::Base

  belongs_to :user
  has_many :icons, :order =&gt; 'position_id ASC' #showing error here..
  has_many :photos, :dependent =&gt; :destroy

end
</code></pre>

<p>Please help.</p>