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End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

class · Ruby 3.1

IOError

< StandardError

Raised when an IO operation fails.

Example
File.open("/etc/hosts") {|f| f << "example"}
  #=> IOError: not opened for writing

File.open("/etc/hosts") {|f| f.close; f.read }
  #=> IOError: closed stream

Note that some IO failures raise SystemCallErrors and these are not subclasses of IOError:

Example
File.open("does/not/exist")
  #=> Errno::ENOENT: No such file or directory - does/not/exist