How to Use Claude Code for Debugging
Claude Code excels at debugging because it reads your entire codebase and traces execution paths across files. It spots subtle bugs and identifies root causes across multiple components.
Plan Mode for Safe Error Analysis
For complex or sensitive bugs, use Plan Mode first. Claude analyzes errors without making changes until you approve the approach, preventing accidental fixes that might break working code.
Paste error messages and stack traces in Plan Mode for thorough investigation. Claude presents a structured investigation plan, then switch to execution mode for implementation. This two-phase approach works best for production bugs, complex issues, or unfamiliar codebases.
Error Analysis Workflow
Start with the full error message and stack trace. Claude interprets cryptic errors and identifies the actual problem beyond symptoms.
Provide context about recent changes: "This error started happening after I added user authentication." Temporal context dramatically narrows investigation scope.
Share relevant code files directly. For complex logic bugs, ask Claude to "trace through the execution path that leads to this error."
Common Debugging Patterns
- Runtime Errors: Ask Claude to analyze specific files and identify where undefined values originate. Often reveals prop, state, or async data loading issues.
- Logic Bugs: Claude traces through functions step-by-step with sample data, spotting mathematical errors, edge cases, or incorrect data structure assumptions.
- Performance Issues: Claude analyzes time complexity, Big O notation, and algorithmic efficiency. Also identifies bottlenecks in rendering logic or data fetching strategies.
- Integration Problems: Claude reviews authentication flows and identifies timing issues, race conditions, or intermittent failure causes.
Advanced Debugging Techniques
- State Analysis: Ask Claude to "examine the Redux state flow and identify where data gets corrupted." Claude traces mutations across actions, reducers, and middleware.
- Cross-File Investigation: Claude traces bugs across multiple files, following imports and dependencies to find root causes spanning component boundaries.
- Pattern Recognition: "This looks similar to a bug we fixed in the payment module. Compare the patterns and suggest if the same solution applies."
- Edge Case Discovery: "What edge cases could cause this function to fail?" Claude tests validation logic with unusual inputs.
Systematic Debugging Process
- Reproduce: "Help me create a minimal test case that reproduces this bug consistently."
- Isolate: "Narrow down which part of this function is causing the issue by adding logging statements."
- Understand: "Explain why this code behaves differently than expected and what the underlying issue is."
- Fix: "Suggest a fix that addresses the root cause without breaking existing functionality."
- Prevent: "What validation or error handling can we add to prevent this type of bug in the future?"
Don't just ask Claude for fixes. Ask Claude to explain why the bug occurred, how to prevent similar issues, and to update your CLAUDE.md with relevant guidelines or checks. This builds both better coding habits and systematic prevention into your project.
See Also: Better Prompts|Model Comparison|Getting Started