EC
Errno::ENOTDIR
RubyERRORNotableFilesystem

Path component is not a directory

Quick Answer

Check File.directory? on path components before performing directory operations.

What this means

Raised when a directory operation is performed on a path component that exists but is a regular file rather than a directory. Maps to POSIX errno 20.

Why it happens
  1. 1Using a file path where a directory is expected (e.g., Dir.entries on a file)
  2. 2A path component in a long path points to a file instead of a directory

Fix

Validate path type before use

Validate path type before use
def ensure_dir(path)
  raise Errno::ENOTDIR, "#{path} is not a directory" unless File.directory?(path)
  path
end

Why this works

File.directory? returns true only if the path exists and is a directory.

Code examples
Reproducing the errorruby
File.write('myfile', 'data')
Dir.entries('myfile')
# Errno::ENOTDIR: Not a directory - myfile
Check before useruby
File.directory?(path) ? Dir.entries(path) : raise("Not a directory: #{path}")
Rescue ENOTDIRruby
begin
  Dir.foreach(candidate) { |f| puts f }
rescue Errno::ENOTDIR
  puts "#{candidate} is a file, not a directory"
end
Sources
Official documentation ↗

Ruby Core Documentation

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