mongodb/mongoid · error · Mongoid::Errors::ImmutableAttribute

Attempted to change the immutable attribute '%{name}' with t

Error message

Attempted to change the immutable attribute '%{name}' with the value: %{value}.

What it means

Error "Attempted to change the immutable attribute '%{name}' with the value: %{value}." thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/persistable/updatable.rb:199

      # Checks to see if the _id field has been modified. If it has, and if
      # the document has already been persisted, this is an error. Otherwise,
      # returns without side-effects.
      #
      # Note that if `Mongoid::Config.immutable_ids` is false, this will do
      # nothing.
      #
      # @raise [ Errors::ImmutableAttribute ] if _id has changed, and document
      #   has been persisted.
      def enforce_immutability_of_id_field!
        # special case here: we *do* allow the _id to be mutated if it was
        # previously nil. This addresses an odd case exposed in
        # has_one/proxy_spec.rb where `person.create_address` would
        # (somehow?) create the address with a nil _id first, before then
        # saving it *again* with the correct _id.

        return unless _id_changed? && !_id_was.nil? && persisted?
        raise Errors::ImmutableAttribute.new(:_id, _id) if Mongoid::Config.immutable_ids

        Mongoid::Warnings.warn_mutable_ids
      end

      # Consolidates all the callback invocations into a single place, to
      # avoid cluttering the logic in #prepare_update.
      #
      # @param [ Array<Document> ] update_children The children that the
      #   :update callbacks will be executed on.
      def run_all_callbacks_for_update(update_children, &block)
        run_callbacks(:commit, with_children: true, skip_if: -> { in_transaction? }) do
          run_callbacks(:save, with_children: false) do
            run_callbacks(:update, with_children: false) do
              run_callbacks(:persist_parent, with_children: false) do
                _mongoid_run_child_callbacks(:save) do
                  _mongoid_run_child_callbacks(:update, children: update_children, &block) # _mongoid_run_child_callbacks :update
                end # _mongoid_run_child_callbacks :save
              end # :persist_parent

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/persistable/updatable.rb:199 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mongodb/mongoid@0da0e23d71 (2026-08-23). Data as JSON: /api/errors/3b7ea371c9d037b1. Report an issue: GitHub.