The sidescroll configuration option was removed, it is alway

Error message

The sidescroll configuration option was removed, it is always enabled now.

What it means

Same removal as the global config.sidescroll= (lib/rails_admin/config.rb:291), but at the per-model list-section level: sections/list.rb:49 registers sidescroll as a deprecated option whose block only prints this ActiveSupport::Deprecation warning. Sidescrolling of the list table is always enabled in the 3.x UI, so the value (true or false) is ignored.

Source

Thrown at lib/rails_admin/config/sections/list.rb:50

        register_instance_option :search_help do
          nil
        end

        register_instance_option :sort_by do
          parent.abstract_model.primary_key
        end

        register_instance_option :scopes do
          []
        end

        register_instance_option :row_css_class do
          ''
        end

        register_deprecated_instance_option :sidescroll do
          ActiveSupport::Deprecation.warn('The sidescroll configuration option was removed, it is always enabled now.')
        end

        def fields_for_table
          visible_fields.partition(&:sticky?).flatten
        end

        register_deprecated_instance_option :sort_reverse do
          ActiveSupport::Deprecation.warn('The sort_reverse configuration option is deprecated and has no effect.')
        end
      end
    end
  end
end

View on GitHub (pinned to 0690a5e62f)

Solutions

Delete the `sidescroll` line from the model's list block — there is no replacement and the behavior cannot be turned off.
To shorten the table instead, hide columns: `list { field :long_description { visible false } }` — fewer visible columns means less horizontal scrolling.
While there, check the same block for sort_reverse (sections/list.rb:57), which is deprecated in the same place.

Example fix

# before
RailsAdmin.config do |config|
  config.model Player do
    list do
      sidescroll false # warns: removed, always enabled
    end
  end
end

# after
RailsAdmin.config do |config|
  config.model Player do
    list do
      field :bio { visible false } # narrow the table instead of disabling sidescroll
    end
  end
end

Defensive patterns

Strategy: validation

Validate before calling

#_initializer audit covering the per-model variant
Dir[Rails.root.join('config/initializers/*.rb')].each do |path|
  File.readlines(path).each_with_index do |line, i|
    puts "#{path}:#{i + 1} remove `sidescroll`" if line =~ /\bsidescroll\b/
  end
end

Prevention

Upgrade rails_admin major versions in a dedicated PR whose only diff is initializer/config migration, reviewed against the CHANGELOG.
Automated grep in CI for known-removed option names (sidescroll, total_columns_width, sort_reverse inside list blocks) keeps them from creeping back.
Exercise each model's index page in a request spec after upgrades — deprecated section options fire only when that section config evaluates.

When it happens

Trigger: A per-model config block containing `list { sidescroll false }` (or true), e.g. `RailsAdmin.config do |c| c.model Player do list { sidescroll false } end end`. The warning prints the first time that model's config is evaluated — typically the first admin request to its index page — and the table still sidescrolls.

Common situations: Model configs migrated unchanged from rails_admin 2.x, where disabling sidescroll restored the old wide-table layout; bulk find-and-replace during upgrades that caught the global setter but missed per-model blocks; deprecation-as-error CI setups failing admin page specs.

Related errors

AI-assisted analysis of railsadminteam/rails_admin@0690a5e62f (2026-08-21). Data as JSON: /api/errors/1ff27159ec3e20cb. Report an issue: GitHub.