Quick Answer

Missing end, bracket, or quote in code.

Understanding the Issue

Ruby expects certain closing keywords (end, }, etc.). This error means it reached EOF before finding them.

The Problem

This code demonstrates the issue:

Ruby Error 
# Problem: Missing end
def hello
  puts "world"
# No end

The Solution

Here's the corrected code:

Ruby Fixed 
# Solution: Add end
def hello
  puts "world"
end

# For blocks:
[1,2,3].each do |n|
  puts n
end

Key Takeaways

Always balance opening/closing keywords.