ViewComponent/view_component · error · ViewComponent::ContentAlreadySetForPolymorphicSlotError

Content for slot SLOT_NAME has already been provided.

Error message

Content for slot SLOT_NAME has already been provided.

What it means

Error "Content for slot SLOT_NAME has already been provided." thrown in ViewComponent/view_component.

Source

Thrown at lib/view_component/slotable.rb:450

      end

      @__vc_set_slots ||= {}

      if slot_definition[:collection]
        @__vc_set_slots[slot_name] ||= []
        @__vc_set_slots[slot_name].push(slot)
      else
        @__vc_set_slots[slot_name] = slot
      end

      slot
    end

    def __vc_set_polymorphic_slot(slot_name, poly_type = nil, *args, **kwargs, &block)
      slot_definition = self.class.registered_slots[slot_name]

      if !slot_definition[:collection] && defined?(@__vc_set_slots) && @__vc_set_slots[slot_name]
        raise ContentAlreadySetForPolymorphicSlotError.new(slot_name)
      end

      poly_def = slot_definition[:renderable_hash][poly_type]

      __vc_set_slot(slot_name, poly_def, *args, **kwargs, &block)
    end
  end
end

View on GitHub (pinned to 9f22c36fa7)

Solutions

1. Provide content for the slot only once: either set it via `with_SLOT(...)` or supply it in the render block, not both.
2. Remove the duplicate `with_SLOT` call or the block content that fills the same slot.

When it happens

Trigger: Thrown at lib/view_component/slotable.rb:450 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of ViewComponent/view_component@9f22c36fa7 (2026-08-23). Data as JSON: /api/errors/8e4385f2ac926e32. Report an issue: GitHub.