{"record":{"id":"1519ddeb8ca5a7c9","repo":"puppetlabs/puppet","slug":"could-not-render-to-format-err","errorCode":null,"errorMessage":"Could not render to %{format}: %{err}","messagePattern":"Could not render to %(.+?): %(.+?)","errorType":"exception","errorClass":"Puppet::Network::FormatHandler::FormatError","httpStatus":null,"severity":"error","filePath":"lib/puppet/network/format_support.rb","lineNumber":116,"sourceCode":"    to_data_hash.to_msgpack(*args)\n  end\n\n  # @deprecated, use to_json\n  def to_pson(*args)\n    to_data_hash.to_pson(*args)\n  end\n\n  def to_json(*args)\n    Puppet::Util::Json.dump(to_data_hash, *args)\n  end\n\n  def render(format = nil)\n    format ||= self.class.default_format\n\n    self.class.get_format(format).render(self)\n  rescue => err\n    # TRANSLATORS \"render\" is a function name and should not be translated\n    raise Puppet::Network::FormatHandler::FormatError, _(\"Could not render to %{format}: %{err}\") % { format: format, err: err }, err.backtrace\n  end\n\n  def mime(format = nil)\n    format ||= self.class.default_format\n\n    self.class.get_format(format).mime\n  rescue => err\n    # TRANSLATORS \"mime\" is a function name and should not be translated\n    raise Puppet::Network::FormatHandler::FormatError, _(\"Could not mime to %{format}: %{err}\") % { format: format, err: err }, err.backtrace\n  end\n\n  def support_format?(name)\n    self.class.support_format?(name)\n  end\n\n  # @comment Document to_data_hash here as it is called as a hook from to_msgpack if it exists\n  # @!method to_data_hash(*args)\n  # @api public","sourceCodeStart":98,"sourceCodeEnd":134,"githubUrl":"https://github.com/puppetlabs/puppet/blob/e227c27540975c25aa22d533a52424a9d2fc886a/lib/puppet/network/format_support.rb#L98-L134","documentation":"Instance-level FormatSupport#render wraps failures from format.render(self) into FormatError 'Could not render to %{format}: %{err}'. The wrapped error is usually an unknown format (get_format raising ArgumentError), a missing to_* method (NotImplementedError), or an exception inside the model's own serializer such as to_data_hash hitting nil state.","triggerScenarios":"obj.render(:msgpack) without msgpack support; obj.render(:bogus) (never registered); rendering an object whose to_data_hash raises on nil fields or bad encoding.","commonSituations":"Custom faces and handlers serializing partially built objects; format names taken straight from request parameters; optional gems absent on one node of the fleet.","solutions":["Render with the class default: obj.render (no argument) uses default_format from supported_formats.","Fix the to_data_hash failure named in %{err} — usually nil handling.","Load the optional gem (msgpack) on every node that must render that format.","Whitelist caller-provided format names against obj.class.supported_formats."],"exampleFix":"# before\npayload = report.render(params[:format]) # FormatError when params[:format] is unsupported\n\n# after\nallowed = report.class.supported_formats.map(&:to_s)\nfmt = allowed.include?(params[:format]) ? params[:format] : report.class.default_format\npayload = report.render(fmt)","handlingStrategy":"validation","validationCode":"fmt = Widget.supported_formats.include?(requested.to_sym) ? requested.to_sym : Widget.default_format\npayload = widget.render(fmt)","typeGuard":null,"tryCatchPattern":"begin\n  widget.render(fmt)\nrescue Puppet::Network::FormatHandler::FormatError => e\n  # %{err} names the cause; retry with the default format\n  widget.render\nend","preventionTips":["Prefer default_format unless a specific format is required.","Validate externally sourced format names against supported_formats.","Make to_data_hash total — handle nils explicitly.","Load serialization gems consistently across the fleet."],"tags":["puppet","ruby","serialization","rendering","formats"],"backgroundTag":"serialization-failed","analyzedSha":"e227c27540975c25aa22d533a52424a9d2fc886a","analyzedAt":"2026-08-21T20:49:46.650Z","schemaVersion":2},"datasetVersion":"2026-08-21T23:17:16.201Z"}