diff --git a/db/migrate/20180426145669_migrate_tax_categories_to_line_items.spree.rb b/db/migrate/20180426145669_migrate_tax_categories_to_line_items.spree.rb
index 80a82ea1af..4ce74249b3 100644
--- a/db/migrate/20180426145669_migrate_tax_categories_to_line_items.spree.rb
+++ b/db/migrate/20180426145669_migrate_tax_categories_to_line_items.spree.rb
@@ -1,8 +1,12 @@
 # This migration comes from spree (originally 20130802022321)
 class MigrateTaxCategoriesToLineItems < ActiveRecord::Migration
   def change
-  	Spree::LineItem.includes(:variant => { :product => :tax_category }).find_in_batches do |line_items|
-  	  line_items.each do |line_item|
+    Spree::LineItem.includes(:variant => { :product => :tax_category }).find_in_batches do |line_items|
+      line_items.each do |line_item|
+        next if line_item.variant.nil?
+        next if line_item.variant.product.nil?
+        next if line_item.product.nil?
+        next unless line_item.product.tax_category.present?
         line_item.update_column(:tax_category_id, line_item.product.tax_category.id)
       end
     end
diff --git a/db/migrate/20180910155506_add_uniqueness_of_order_id_to_spree_shipments.rb b/db/migrate/20180910155506_add_uniqueness_of_order_id_to_spree_shipments.rb
index 21ad966ad4..34d509111e 100644
--- a/db/migrate/20180910155506_add_uniqueness_of_order_id_to_spree_shipments.rb
+++ b/db/migrate/20180910155506_add_uniqueness_of_order_id_to_spree_shipments.rb
@@ -1,6 +1,89 @@
+# This migration is an OFN specific migration that enforces an order to have a single shipment at all times
 class AddUniquenessOfOrderIdToSpreeShipments < ActiveRecord::Migration
   def change
+    destroy_all_but_latest_shipments
+
     remove_index :spree_shipments, :order_id
     add_index :spree_shipments, :order_id, unique: true
   end
+
+  private
+
+  # Destroy all but the latest shipment in each order
+  def destroy_all_but_latest_shipments
+    latest_shipments = Spree::Shipment.
+      select("order_id, MAX(updated_at) updated_at").
+      group(:order_id).
+      having("count(*) > 1")
+
+    all_duplicated_shipments = Spree::Shipment.
+      joins("INNER JOIN (#{latest_shipments.to_sql}) latest_shipments ON spree_shipments.order_id = latest_shipments.order_id")
+    backup_to_csv(all_duplicated_shipments)
+
+    shipments_to_delete = Spree::Shipment.
+      joins("INNER JOIN (#{latest_shipments.to_sql}) latest_shipments ON spree_shipments.order_id = latest_shipments.order_id AND spree_shipments.updated_at != latest_shipments.updated_at")
+    remove_association_to_adjustments(shipments_to_delete)
+    shipments_to_delete.destroy_all
+  end
+
+  def remove_association_to_adjustments(shipments)
+    Spree::Adjustment.
+      joins("INNER JOIN (#{shipments.to_sql}) shipments_to_delete ON shipments_to_delete.id = spree_adjustments.source_id and spree_adjustments.source_type = 'Spree::Shipment'").
+      update_all(source_id: nil, source_type: nil, originator_id: nil, originator_type: nil, mandatory: nil)
+  end
+
+  def backup_to_csv(shipments)
+    CSV.open(csv_path, "w") do |csv|
+      csv << csv_header_row
+
+      shipments.each do |shipment|
+        csv << shipment_csv_row(shipment)
+      end
+    end
+  end
+
+  def csv_header_row
+    %w(
+      id
+      tracking
+      number
+      order_number
+      shipping_method_name
+      cost
+      state
+      shipped_at
+      created_at
+      updated_at
+      address_json
+    )
+  end
+
+  def shipment_csv_row(shipment)
+    [
+      shipment.id,
+      shipment.tracking,
+      shipment.number,
+      shipment.order.number,
+      shipment.shipping_method.andand.name,
+      shipment.cost,
+      shipment.state,
+      shipment.shipped_at,
+      shipment.created_at,
+      shipment.updated_at,
+      shipment.address.to_json
+    ]
+  end
+
+  def csv_path
+    ensure_reports_path_exists
+    reports_path.join("duplicated_shipments_backup.csv")
+  end
+
+  def reports_path
+    Rails.root.join("reports")
+  end
+
+  def ensure_reports_path_exists
+    Dir.mkdir(reports_path) unless File.exist?(reports_path)
+  end
 end