title: NameError Exception: uninitialized constant ActiveStorage::Attachment::ActiveStorage::Blob
body: <p>I am trying to use my Rails database and keep running into this error. The database was working previously with no active storage issues until 5 days ago when it stopped and I started seeing this error:</p>
  
  <p><code>*** NameError Exception: uninitialized constant ActiveStorage::Attachment::ActiveStorage::Blob</code></p>
  
  <p>I have a .jbuilder file that is where the error is happening, </p>
  
  <pre><code>json.array! @campaigns do |campaign|
      byebug
      json.extract! campaign, :id, :title, :description, :goal, :campaign_end, :user_id, :current_amount, :ends, :percent_complete, :amount_left_to_fund, :owner, :successful
      json.photoUrl url_for(campaign.photo)
  end
  </code></pre>
  
  <p>Where it says url_for(campaign.photo) I get the error. However, just typing campaign.photo shows the ActiveStorage instance with the campaign it is attached to: </p>
  
  <pre><code>#&lt;ActiveStorage::Attached::One:0x00007febc64f91b0 @name="photo", @record=#&lt;Campaign id: 7, title: "Surgery", description: "Lorem ipsum dolor sit amet, consectetur adipiscing...", goal: 5000, user_id: 8, campaign_end: "2019-05-31 16:00:00", created_at: "2019-05-01 14:20:14", updated_at: "2019-05-01 14:20:14", successful: false&gt;, @dependent=:purge_later&gt;
  </code></pre>
  
  <p>I am just trying to get the url for this active storage photo. I tried googling this error but haven't seen anything with this error message. Any help would be much appreciate!</p>