A comprehensive exploration of advanced WordPress debugging techniques, equipping learners with the skills and tools needed to troubleshoot and resolve complex issues in WordPress applications.

From cultivating a debugging mindset and mastering essential tools like Query Monitor, Xdebug, and browser developer tools, to tackling real-world scenarios such as database issues, REST API errors, and total site failure, the course provides hands-on guidance for every stage of the debugging process.

Advanced WordPress Debugging Overview

Lessons

About Advanced WordPress Debugging

Introduction to WordPress Debugging (Debugging Mindset)

Lessons

What Do We Mean by Debugging? How to Develop Debugging Skills How Do We Know Something Needs Debugging? Defining the Problem Challenge: Developing Your Personal Approach

Tools and Techniques For Debugging

Lessons

Overview of Tools and Techniques Used for Debugging Debug bar Query Monitor PHP Logs – Errors, Warnings, and Notices Xdebug Application Performance Monitoring (APM) Tools Using Non-Production Remote Environments for Debugging Browser Dev Tools Examining Request and Response Headers Curl Graphical HTTP Clients Custom Host File Entries Debugging using Actions and Filters Debugging Using Terminal-Based Tools Debugging Using WP-CLI Commands Debugging Using WordPress Shell PHPCS Static Analysis Database GUI Tools Connecting to Remote Databases via SSH Tunnel Site Info and Site Health in WordPress Admin IDE Customisations – VS Code Debug Tooling for the WordPress VIP Platform

Writing Custom Debugging Code

Lessons

Writing Custom Debugging Code Custom Response Headers In WordPress Custom WP-CLI commands Debugging Using Custom Logs Extending Query Monitor with a Custom Panel for Debugging

Debugging in a Local Environment

Lessons

Using a Local Development Environment for Debugging Studio by WordPress.com wp-env WordPress Playground and wp-now VIP Local Development Environment Using Virtualbox and Other Virtual Machines Vagrant and VVV Using Docker for Local WordPress Debugging Choosing Local Environment Tooling That Works for You and Your Team

WordPress Application Debugging Scenarios

Lessons

White Screen of Death (WSOD) Debugging WP Object Cache Issues Redirect Loops and Unexplained Redirects Debugging in Production Intermittent Issues Bypassing Code and Plugins Replaying HTTP Requests when Debugging Rest API and AJAX Endpoints Out of Memory Issues Debugging REST API Requests Understanding Stack Traces Working with Core Code Debugging Server-side HTTP Requests Debugging Cookie Issues Client-Side JavaScript Debugging Debugging Headless/ Decoupled WordPress

Debugging WordPress Database Issues

Lessons

Database Connection Issues Slow Database Queries Indexes, Autoincrement and Table Types Counting Database Tables Table Sizes Options Table

WordPress Debugging Case Studies

Lessons

Case Study – Disappearing Sidebar Widgets on a Busy News Multisite Network Case Study – Intermittent Out Of Memory Errors Case Study – Finding The Source of Rogue Newline Output

Test Your Knowledge

Lessons

Quiz