RuntimeError

RuntimeError is a generic error class raised when something goes wrong during program execution. It's the default exception type when you call raise without specifying an exception class.

Common causes

• Explicit raise without exception class
• Modifying frozen objects
• Thread synchronization issues
• Generic error conditions in libraries
• Failed assertions or validations

How to fix it

• Read the error message for specific cause
• Check if object is frozen before modifying
• Use proper synchronization for threads
• Handle with begin/rescue blocks
• Create custom exception classes for specific errors

Example

# Error example
raise "Something went wrong"  # => RuntimeError: Something went wrong

# Frozen object example
str = "hello".freeze
str << " world"  # => FrozenError (subclass of RuntimeError)

# Proper error handling
begin
  risky_operation
rescue RuntimeError => e
  logger.error("Operation failed: #{e.message}")
end