puppetlabs/puppet · error · Serialization::SerializationError

Initializer for class #{impl_class.name} parameter '#{ip}' d

Error message

Initializer for class #{impl_class.name} parameter '#{ip}' does not match any of the attributes of type #{name}

What it means

Companion to the initializer arity check in parameter_info: when the Ruby implementation class's initialize parameter list is the right size but a parameter name matches none of the Object type's attributes, Puppet cannot map constructor arguments to attributes and raises Serialization::SerializationError naming the offending parameter.

Source

Thrown at lib/puppet/pops/types/p_object_type.rb:658

        # assert that the protected name wasn't a real name (names can start with underscore)
        n = r unless param_names.index(r).nil?
      end
      n
    end

    if init_param_names != param_names
      if init_param_names.size < param_count || init_non_opt_count > param_count
        raise Serialization::SerializationError, "Initializer for class #{impl_class.name} does not match the attributes of #{name}"
      end

      init_param_names = init_param_names[0, param_count] if init_param_names.size > param_count
      unless init_param_names == param_names
        # Reorder needed to match initialize method arguments
        new_param_types = []
        init_param_names.each do |ip|
          index = param_names.index(ip)
          if index.nil?
            raise Serialization::SerializationError,
                  "Initializer for class #{impl_class.name} parameter '#{ip}' does not match any of the attributes of type #{name}"
          end
          new_param_types << param_types[index]
        end
        param_names = init_param_names
        param_types = new_param_types
      end
    end

    pic = [param_names.freeze, param_types.freeze, non_opt_types.size].freeze
    @parameter_info[impl_class] = pic
    pic
  end

  # @api private
  def attr_reader_name(se)
    if se.value_type.is_a?(PBooleanType) || se.value_type.is_a?(POptionalType) && se.value_type.type.is_a?(PBooleanType)
      "#{se.name}?"

View on GitHub (pinned to e227c27540)

Solutions

Rename the initialize parameter to exactly match the declared attribute name
If the name is correct in initialize, add or fix the attribute in the interface so the two agree
Remove the stray parameter entirely if it corresponds to no attribute

Example fix

# before
type attributes: { x => Integer, y => Integer, z => Integer }
def initialize(x, y, w)      # 'w' matches no attribute
  ...
end

# after
def initialize(x, y, z)
  ...
end

Defensive patterns

Strategy: validation

Validate before calling

# assert every initialize parameter name is an attribute name
attr_names = type.attributes(true).keys
params = impl_class.instance_method(:initialize).parameters.map { |_, n| n.to_s }
unknown = params - attr_names
abort "initialize parameters not matching any attribute: #{unknown.inspect}" unless unknown.empty?

Try / catch

begin
  type.create(*args)
rescue Puppet::Pops::Serialization::SerializationError => e
  raise unless e.message =~ /parameter '.*' does not match any of the attributes/
  # e.message names the offending parameter; fix the impl class signature
  raise
end

Prevention

Name initialize parameters exactly after the declared attributes
Run a startup assertion comparing parameter names with attribute names (see validationCode)
Rename attributes and initialize parameters together in one refactor

When it happens

Trigger: initialize has a parameter whose name is not an attribute of the type: a typo (w vs z), a renamed attribute still referenced by the old name in initialize, or an extra positional parameter with a default value that shadows no attribute.

Common situations: Renaming an attribute in the interface string while leaving the implementation class unchanged; hand-written implementation classes whose initialize uses different names than the declarative attributes; copy-paste between similar types.

Related errors

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/610256a9a10e5d73. Report an issue: GitHub.