puppetlabs/puppet · error · ArgumentError

Name must be a String not

Error message

Name must be a String not %{klass}

What it means

The package type's name parameter (a namevar) validates that it is a String: arrays, nil/undef, hashes, or symbols raise "Name must be a String not %{klass}". One package resource manages exactly one package name.

Solutions

1. Set name to a single string: `name => 'openssl'`.
2. For multiple packages iterate: `['a','b'].each |$p| { package { $p: ensure => installed } }`.
3. Fix Hiera so the key resolves, and guard with `assert_type(String, $name)`.
4. In Ruby, fail loudly on nil instead of coercing it to the string 'nil'.

Example fix

// before
package { 'ssh': name => ['openssh-server', 'openssh-client'] }

// after
['openssh-server', 'openssh-client'].each |$p| {
  package { $p: ensure => installed }
}

// Puppet: guard Hiera-sourced names
$name = assert_type(String, $name)

def package_name_ok?(v)
  v.is_a?(String) && !v.empty?
end

When it happens

Trigger: `package { 'foo': name => ['a', 'b'] }`; a Hiera lookup where the name key resolves to undef; ENC or Ruby code passing a hash/symbol; note that array titles like `package { ['a','b']: }` are fine — only an explicit non-string name parameter raises.

Common situations: Hiera data missing the name key after refactors; external tools emitting lists into name; assuming array-title semantics apply to the name parameter; params classes defaulting name to undef.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• value of must be a hash
• all keys must start with module name
• all patterns must match a key starting with module name
• Argument to 'return_type' must be a String reference to a…
• Cannot have both `enable_only => true` and `flavor`

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/491adf1ec7ce5c22. Report an issue: GitHub.

Appendix: source

Thrown at lib/puppet/type/package.rb:274

          ...

          $ssh = $os['name'] ? {
            solaris => SMCossh,
            default => openssh
          }

          package { 'openssh':
            ensure  => installed,
            name    => $ssh,
            require => Package['openssl'],
          }

      "
      isnamevar

      validate do |value|
        unless value.is_a?(String)
          raise ArgumentError, _("Name must be a String not %{klass}") % { klass: value.class }
        end
      end
    end

    # We call providify here so that we can set provider as a namevar.
    # Normally this method is called after newtype finishes constructing this
    # Type class.
    providify
    paramclass(:provider).isnamevar

    def self.parameters_to_include
      [:provider]
    end

    # Specify a targeted package management command.
    newparam(:command, :required_features => :targetable) do
      desc <<-EOT
        The targeted command to use when managing a package:

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