diff --git a/back/.rubocop_todo.yml b/back/.rubocop_todo.yml
index 3b36fe322e06..b32f74823131 100644
--- a/back/.rubocop_todo.yml
+++ b/back/.rubocop_todo.yml
@@ -201,6 +201,7 @@ RSpec/DescribeClass:
     - 'spec/tasks/single_use/migrate_homepage_craftjson_task_spec.ignore.rb'
     - 'spec/tasks/single_use/rename_gv_profile_spec.ignore.rb'
     - 'spec/tasks/single_use/substitute_cl_gv_task_spec.ignore.rb'
+    - 'spec/tasks/single_use/custom_field_orderings_spec.ignore.rb'
 
 # Offense count: 149
 # This cop supports safe autocorrection (--autocorrect).
@@ -337,6 +338,7 @@ RSpec/SpecFilePathSuffix:
     - 'spec/tasks/single_use/move_ideation_custom_forms_to_project_spec.ignore.rb'
     - 'spec/tasks/single_use/rename_gv_profile_spec.ignore.rb'
     - 'spec/tasks/single_use/substitute_cl_gv_task_spec.ignore.rb'
+    - 'spec/tasks/single_use/custom_field_orderings_spec.ignore.rb'
 
 # Offense count: 77
 RSpec/StubbedMock:
diff --git a/back/lib/tasks/single_use/20251103_custom_fields_orderings.rake b/back/lib/tasks/single_use/20251103_custom_fields_orderings.rake
new file mode 100644
index 000000000000..53a966c834e4
--- /dev/null
+++ b/back/lib/tasks/single_use/20251103_custom_fields_orderings.rake
@@ -0,0 +1,51 @@
+namespace :fix_existing_tenants do
+  desc 'Fix custom fields orderings and make sure the first field is a page.'
+  task :custom_fields_orderings, [] => [:environment] do
+    reporter = ScriptReporter.new
+    Tenant.all.each do |tenant|
+      tenant.switch do
+        # rubocop:disable Performance/CollectionLiteralInLoop
+        ([nil] + CustomForm.all).each do |form|
+          fields = CustomField.where(resource_id: form&.id).order(:ordering)
+
+          # Check if ordering is correct
+          next if fields.pluck(:ordering) == (0...fields.size).to_a
+
+          # Fix orderings
+          fields.each.with_index do |field, index|
+            field.update_column(:ordering, index)
+          end
+          reporter.add_change(
+            nil,
+            'Fixed orderings',
+            context: { tenant: tenant.host, form: form&.id }
+          )
+
+          # First field must be a page
+          next if !form
+
+          fields = CustomField.where(resource_id: form.id).order(:ordering)
+          next if fields.first.page?
+
+          first_page = fields.find(&:page?)
+          if !first_page
+            reporter.add_error(
+              'Form has no pages!',
+              context: { tenant: tenant.host, form: form.id }
+            )
+            next
+          end
+
+          first_page.move_to_top
+          reporter.add_change(
+            nil,
+            'Page moved to top',
+            context: { tenant: tenant.host, form: form.id, page: first_page.id }
+          )
+        end
+        # rubocop:enable Performance/CollectionLiteralInLoop
+      end
+    end
+    reporter.report!('fix_custom_fields_orderings_report.json', verbose: true)
+  end
+end
diff --git a/back/spec/tasks/single_use/custom_field_orderings_spec.ignore.rb b/back/spec/tasks/single_use/custom_field_orderings_spec.ignore.rb
new file mode 100644
index 000000000000..d3108f760797
--- /dev/null
+++ b/back/spec/tasks/single_use/custom_field_orderings_spec.ignore.rb
@@ -0,0 +1,45 @@
+require 'rails_helper'
+
+describe 'fix_existing_tenants:custom_fields_orderings rake task' do
+  before { load_rake_tasks_if_not_loaded }
+
+  it 'Fixes the orderings' do
+    form1 = create(:custom_form)
+    create(:custom_field, resource: form1, input_type: 'number', key: 'field2')
+    create(:custom_field_page, resource: form1, key: 'field1').update_column(:ordering, 0)
+    create(:custom_field, resource: form1, input_type: 'number', key: 'field3').update_column(:ordering, 3)
+    create(:custom_field, resource: form1, input_type: 'text', key: 'field4').update_column(:ordering, 3)
+    create(:custom_field_page, resource: form1, key: 'field5').update_column(:ordering, 4)
+
+    form2 = create(:custom_form)
+    create(:custom_field_page, resource: form2, key: 'field1')
+    create(:custom_field, resource: form2, input_type: 'number', key: 'field2')
+    create(:custom_field, resource: form2, input_type: 'text', key: 'field3')
+    create(:custom_field_page, resource: form2, key: 'field4')
+
+    create(:custom_field, resource_id: nil, resource_type: 'User', input_type: 'text', key: 'field1')
+    create(:custom_field, resource_id: nil, resource_type: 'User', input_type: 'number', key: 'field2').update_column(:ordering, 2)
+
+    Rake::Task['fix_existing_tenants:custom_fields_orderings'].invoke
+
+    expect(form1.reload.custom_fields.pluck(:key, :ordering)).to eq([
+      ['field1', 0],
+      ['field2', 1],
+      ['field3', 2],
+      ['field4', 3],
+      ['field5', 4]
+    ])
+
+    expect(form2.reload.custom_fields.pluck(:key, :ordering)).to eq([
+      ['field1', 0],
+      ['field2', 1],
+      ['field3', 2],
+      ['field4', 3]
+    ])
+
+    expect(CustomField.where(resource_id: nil).order(:ordering).pluck(:key, :ordering)).to eq([
+      ['field1', 0],
+      ['field2', 1]
+    ])
+  end
+end