Jekyll Config YML Error Fix

In this tutorial, you'll learn about Jekyll Config YML Error Fix. We cover key concepts, practical examples, and best practices.

The Problem

Error:  (<unknown>): did not find expected key while parsing a block mapping at line 6 column 3

Jekyll's YAML parser is strict about indentation. A misaligned value causes the entire build to fail.

Wrong

title: My Site
description: A great site
  author: John Doe

Output: did not find expected key while <a href="/compiler-design/syntax-analysis/">parsing</a> a block mapping

The author key is indented under description, making it a nested value instead of a top-level key.

Right

title: My Site
description: A great site
author: John Doe

Output: build succeeds with all config values parsed correctly.

Use double quotes for values containing colons or special characters:

title: "My Site: The Blog"
description: "Tips & tricks for developers"

Prevention

• Use consistent indentation (2 spaces, no tabs)
• Validate YAML with ruby -e "require 'yaml'; puts YAML.load_file('_config.yml')"
• Quote values with special characters

Common Mistakes with config yml

1. Using head and tail instead of pattern matching, causing runtime errors on empty lists
2. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
3. Using return to exit a function early instead of wrapping a pure value in the monad

These mistakes appear frequently in real-world JEKYLL code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ