urbanadventurer/WhatWeb · error

You must specify the available versions of the product

Error message

You must specify the available versions of the product

What it means

Version#initialize in WhatWeb's version_class.rb requires a product name, an available-versions value, and a URL. When the `versions` argument is nil (or omitted), the constructor raises this error before any instance state is set. It is a guard against creating a Version object that has no version data to compare or download against.

Solutions

1. Pass a non-nil versions value as the second argument to Version.new, e.g. an array or string of versions
2. Check the variable feeding the versions argument for nil before constructing the Version
3. Verify argument order: initialize(name_product, versions, url) — ensure url was not shifted into the versions slot
4. Default to an empty-but-non-nil structure like [] if the caller intentionally has no known versions

Example fix

// before
v = Version.new('Apache', nil, 'http://example.com')
// after
v = Version.new('Apache', ['2.4.57', '2.4.58'], 'http://example.com')

raise ArgumentError, 'versions is required' if versions.nil?
v = Version.new('Apache', versions, 'http://example.com')

def valid_versions?(v)
  !v.nil?
end

When it happens

Trigger: Calling Version.new(name, nil, url) or Version.new(name, url: ...) with the second positional argument omitted, or passing a variable that evaluated to nil (e.g. an empty lookup result used as the versions argument).

Common situations: Plugins or helper scripts construct a Version to fetch version-specific files after a match, but the versions list was never populated because an earlier scrape/regex found nothing; positional-argument mix-ups where url is passed as the second argument leaving versions nil.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• You must specify the available url of the website
• No target
• Error parsing target IP range: #
• Unable to parse invalid target. No hostname.
• You must specify the name of the product

AI-assisted analysis of urbanadventurer/WhatWeb@d279d93042 (2026-09-15). Data as JSON: /api/errors/3508a19c06b7b10b. Report an issue: GitHub.

Appendix: source

Thrown at lib/version_class.rb:21

# This file is part of WhatWeb.
#
# WhatWeb is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# at your option) any later version.
#
# WhatWeb is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with WhatWeb.  If not, see <http://www.gnu.org/licenses/>.

class Version
  def initialize(name_product = nil, versions = nil, url = nil)
    raise 'You must specify the name of the product' if name_product.nil?
    raise 'You must specify the available versions of the product' if versions.nil?
    raise 'You must specify the available url of the website' if url.nil?

    @name = name_product
    @versions = versions
    @files = Hash['filenames' => [], 'files' => [], 'md5' => []]
    @url = url
    @got_best_versions = false
    @best_versions = []

    versions.each do |version|
      version[1].each do |file|
        next if @files['filenames'].include? file[0]
        @files['filenames'].push(file[0])
        @files['files'].push(URI.join(@url.to_s, file[0]).to_s)
        _status, url, _ip, body, _headers = open_target(@files['files'].last)
        @files['md5'].push(Digest::MD5.hexdigest(body))
      end
    end

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