SeleniumHQ/selenium · error · ArgumentError

Cookie name cannot be null or empty

Error message

Cookie name cannot be null or empty

What it means

Manager#delete_cookie requires a non-nil, non-blank cookie name. It explicitly rejects nil, empty strings, and whitespace-only names by calling name.to_s.strip.empty?. This guards against sending an invalid delete request to the driver endpoint.

Source

Thrown at rb/lib/selenium/webdriver/common/manager.rb:82

      #
      # Get the cookie with the given name
      #
      # @param [String] name the name of the cookie
      # @return [Hash] the cookie, or throws a NoSuchCookieError if it wasn't found.
      #

      def cookie_named(name)
        convert_cookie(@bridge.cookie(name))
      end

      #
      # Delete the cookie with the given name
      #
      # @param [String] name the name of the cookie to delete
      #

      def delete_cookie(name)
        raise ArgumentError, 'Cookie name cannot be null or empty' if name.nil? || name.to_s.strip.empty?

        @bridge.delete_cookie name
      end

      #
      # Delete all cookies
      #

      def delete_all_cookies
        @bridge.delete_all_cookies
      end

      #
      # Get all cookies
      #
      # @return [Array<Hash>] list of cookies
      #

View on GitHub (pinned to aa36b38e69)

Solutions

1. Ensure the name variable is a non-empty String before calling delete_cookie.
2. Filter blank entries from the name list: names.compact.reject(&:empty?).
3. Default to a guard clause: next if name.nil? || name.strip.empty?

Example fix

# before
driver.manage.delete_cookie(name) # name may be nil

# after
if name && !name.to_s.strip.empty?
  driver.manage.delete_cookie(name)
end

next if name.nil? || name.to_s.strip.empty?
driver.manage.delete_cookie(name)

def valid_cookie_name?(name)
  name.is_a?(String) && !name.strip.empty?
end

begin
  driver.manage.delete_cookie(name)
rescue ArgumentError => e
  raise unless e.message.include?('null or empty')
  # skip or log; name was invalid
end

When it happens

Trigger: Calling driver.manage.delete_cookie(nil). Passing an empty string delete_cookie('') or whitespace delete_cookie(' '). Reading a name from a variable that resolved to nil.

Common situations: Looping over a list of names that contains nil/blank entries. UI-driven input that yields an empty cookie name. Forgetting to check user input before deletion.

Related errors

• name is required
• Params must be an instance of CookieFilter. Received:'${cook
• Cookie name cannot be empty
• invalid value for expiration date: #{obj.inspect}
• Invalid page size: #{value}

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/17ac80dcdc136ac9. Report an issue: GitHub.