SeleniumHQ/selenium · error · Error::WebDriverError

Don't know how to handle #{kind} events

Error message

Don't know how to handle #{kind} events

What it means

HasLogEvents#on_log_event registers a listener for one of a fixed set of log event kinds (:console, :exception, :mutation). Passing any other kind raises Error::WebDriverError because there is no log_<kind>_events method to invoke. This is a Chromium/DevTools-backed feature.

Source

Thrown at rb/lib/selenium/webdriver/common/driver_extensions/has_log_events.rb:60

        # @example Collect JavaScript exceptions
        #   exceptions = []
        #   driver.on_log_event(:exception) do |event|
        #     exceptions.push(event)
        #   end
        #
        # @example Collect DOM mutations
        #   mutations = []
        #   driver.on_log_event(:mutation) do |event|
        #     mutations.push(event)
        #   end
        #
        # @param [Symbol] kind :console, :exception or :mutation
        # @param [#call] block which is called when event happens
        # @yieldparam [DevTools::ConsoleEvent, DevTools::ExceptionEvent, DevTools::MutationEvent]
        #

        def on_log_event(kind, &block)
          raise Error::WebDriverError, "Don't know how to handle #{kind} events" unless KINDS.include?(kind)

          enabled = log_listeners[kind].any?
          log_listeners[kind] << block
          return if enabled

          devtools.runtime.enable
          __send__(:"log_#{kind}_events")
        end

        private

        def log_listeners
          @log_listeners ||= Hash.new { |listeners, kind| listeners[kind] = [] }
        end

        def log_console_events
          devtools.runtime.on(:console_api_called) do |params|
            event = DevTools::ConsoleEvent.new(

View on GitHub (pinned to aa36b38e69)

Solutions

1. Use one of :console, :exception, or :mutation.
2. Pass a Symbol, not a String.
3. For other event types, use the lower-level BiDi or DevTools APIs directly instead of on_log_event.

Example fix

// before
driver.on_log_event('console') { |e| ... }
driver.on_log_event(:network) { |e| ... }
// after
driver.on_log_event(:console) { |e| ... }

VALID_LOG_KINDS = %i[console exception mutation].freeze

raise ArgumentError, "unknown log kind #{kind}" unless VALID_LOG_KINDS.include?(kind.to_sym)
driver.on_log_event(kind.to_sym, &block)

def valid_log_kind?(kind)
  %i[console exception mutation].include?(kind.to_sym)
end

begin
  driver.on_log_event(kind, &block)
rescue Selenium::WebDriver::Error::WebDriverError => e
  raise unless e.message =~ /Don't know how to handle/
  warn "use :console, :exception, or :mutation"
end

When it happens

Trigger: Calling driver.on_log_event(:network) { ... } or any kind not in KINDS = %i[console exception mutation].

Common situations: Typo in the kind symbol, expecting a kind that does not exist (e.g. :network, :error), passing a String instead of a Symbol, copying examples that assume more kinds than implemented.

Related errors

• Could not find a valid devtools version; use a more recent v
• Unknown pattern type: #{pattern_type}
• unknown driver: #{browser.inspect}
• detector must respond to #call
• CDP devtools module not loaded. Call import_devtools() first

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/86784fd018cd1648. Report an issue: GitHub.