ArgumentError

ArgumentError is raised when a method receives an argument it cannot handle. This includes wrong number of arguments, invalid argument values, or incompatible argument types.

Common causes

• Wrong number of arguments passed to a method
• Passing nil when a value is required
• Invalid argument format (e.g., invalid date string)
• Missing required keyword arguments
• Extra unexpected keyword arguments

How to fix it

• Check the method signature for required arguments
• Validate arguments before passing them
• Use default values for optional arguments
• Check documentation for expected argument format
• Use **kwargs to accept arbitrary keyword arguments

Example

# Error example
def greet(name)
  "Hello, #{name}!"
end
greet()  # => ArgumentError: wrong number of arguments (given 0, expected 1)

# Fix by providing the argument
greet("World")  # => "Hello, World!"

# Or add a default value
def greet(name = "World")
  "Hello, #{name}!"
end

Related errors