jdx/mise · error · RuntimeError

no cask block found

Error message

no cask block found

What it means

At the bottom of the tap cask metadata eval script, the parsed cask metadata is held in `$mise_cask_metadata`, which is only assigned when a `cask ... do ... end` block actually executes. If the evaluated cask file contained no such block (so the global stays nil), the script raises 'no cask block found' before serializing JSON. It's a sanity gate ensuring a cask was actually parsed.

Source

Thrown at src/system/packages/brew/tap_cask_metadata.rb:292

  def respond_to_missing?(*) = true

  private

  def add_artifact(kind, source, target)
    value = [source.to_s]
    value << { "target" => target.to_s } unless target.nil?
    @artifacts << { kind => value }
  end
end

def cask(token, &block)
  $mise_cask_metadata = CaskMetadata.new(token)
  $mise_cask_metadata.instance_eval(&block)
end

eval(STDIN.read.force_encoding("UTF-8"), TOPLEVEL_BINDING, CASK_FILE, 1)
metadata = $mise_cask_metadata
raise "no cask block found" if metadata.nil?
expected = ENV.fetch("MISE_BREW_TOKEN")
raise "expected cask #{expected}, got #{metadata.token}" if metadata.token != expected
puts JSON.generate(metadata.to_h)

View on GitHub (pinned to afd2eddd3a)

Solutions

1. Ensure the file evaluated is a cask and begins with a top-level `cask ... do` block
2. Verify the path/env (CASK_FILE / MISE_BREW_TOKEN) selects the intended cask file in the tap
3. Re-fetch the tap if the cask file is empty or truncated
4. Check the cask block isn't guarded by a conditional that prevents it from executing at top level

Example fix

# before (evaluated file)
# empty or formula content
# after
cask 'mytool' do
  version '1.2.3'
  url 'https://example.com/mytool-1.2.3.zip'
  sha256 :no_check
end

src = File.read(cask_path)
raise 'not a cask file' unless src.match?(/^\s*cask\s+['\"]/)

begin
  run_cask_metadata_extraction(cask_path)
rescue RuntimeError => e
  raise unless e.message == 'no cask block found'
  # verify the path points at a cask, not a formula or empty file
end

When it happens

Trigger: The file piped to STDIN and eval'd contains no top-level `cask '<token>' do ... end` block — e.g. it's a formula (.rb formula), an unrelated Ruby file, an empty/truncated file, or the cask DSL itself failed earlier in a way that skipped the block.

Common situations: Pointing the tap metadata extraction at a formula instead of a cask; wrong file path/env var so an empty file is read; cask file that wraps everything in conditionals the top-level binding doesn't execute; tap layout changes moving casks to new paths.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

• cask has no version
• cask has no URL
• unsupported cask metadata DSL `#{name}`
• no precompiled ruby is available for this platform To compil
• Ruby engine '{}' is not supported on Windows. Only standard

AI-assisted analysis of jdx/mise@afd2eddd3a (2026-09-09). Data as JSON: /api/errors/a1e7cd11ceec6020. Report an issue: GitHub.