SeleniumHQ/selenium · error · Error::WebDriverError

unknown HTTP verb: #{verb.inspect}

Error message

unknown HTTP verb: #{verb.inspect}

What it means

Raised as Error::WebDriverError by the Curb HTTP client adapter (Http::Curb) when the HTTP verb passed to request is not one of :get, :post, :put, :delete, or :head. The adapter maps known verbs to Curl::Easy methods; any other symbol/string falls through the case/when to this error.

Source

Thrown at rb/lib/selenium/webdriver/remote/http/curb.rb:78

            # http://github.com/taf2/curb/issues/issue/33
            client.head = false
            client.delete = false

            case verb
            when :get
              client.http_get
            when :post
              client.post_body = payload || ''
              client.http_post
            when :put
              client.put_data = payload || ''
              client.http_put
            when :delete
              client.http_delete
            when :head
              client.http_head
            else
              raise Error::WebDriverError, "unknown HTTP verb: #{verb.inspect}"
            end

            create_response client.response_code, client.body_str, client.content_type
          end

          def client
            @client ||= begin
              c = Curl::Easy.new

              c.max_redirects = MAX_REDIRECTS
              c.follow_location = true
              c.timeout = timeout if timeout
              c.verbose = WebDriver.logger.debug?
              c
            end
          end
        end # Curb
      end # Http

View on GitHub (pinned to aa36b38e69)

Solutions

1. Ensure all registered command verbs are one of :get, :post, :put, :delete, :head (as Symbols).
2. If you registered a custom command, verify the verb in the command tuple: [:patch, '/path'] is NOT supported by curb — use :put or switch to the Default (Net::HTTP) adapter.
3. Use the Default HTTP adapter (Net::HTTP) if you need broader verb support: Selenium::WebDriver::Remote::Http::Default.new.

Example fix

# before — curb does not support :patch
bridge.add_commands({custom: [:patch, '/session/:session_id/custom']})

# after — use a supported verb, or switch adapter
bridge.add_commands({custom: [:post, '/session/:session_id/custom']})
# or use Default adapter which may support more verbs

# Validate verb before registering custom commands with curb:
SUPPORTED_VERBS = %i[get post put delete head].freeze
unless SUPPORTED_VERBS.include?(verb)
  raise ArgumentError, "curb adapter does not support verb #{verb}"
end

def curb_supported_verb?(verb)
  %i[get post put delete head].include?(verb)
end

begin
  http_client.request(verb, url)
rescue Selenium::WebDriver::Error::WebDriverError => e
  raise unless e.message.include?('unknown HTTP verb')
  raise "Use Default (Net::HTTP) adapter for verb #{verb}"
end

When it happens

Trigger: Using the curb adapter with a custom command that registers a non-standard HTTP verb. Passing a String verb like 'GET' instead of Symbol :get (the case uses symbols). A typo or uppercase verb symbol. A command registration bug producing an unexpected verb.

Common situations: Registering custom commands with add_commands using a verb the curb adapter doesn't handle. Switching from the default (Net::HTTP) adapter to curb without verifying all commands use supported verbs. Framework code that builds verbs dynamically producing incorrect values.

Related errors

• Cannot use both :http_client and :client_config
• #{opts.inspect} invalid for #{command.inspect}
• Cannot use both :http_client and :client_config
• Cannot use both :client_config and :open_timeout/:read_timeo
• too many redirects

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/7ab5c322c1b75df3. Report an issue: GitHub.