Debugging with Claude Code

Share error messages effectively with Claude Code

Let Claude trace issues through your codebase

Provide reproduction steps for better debugging

Fix root causes rather than symptoms

Use the /debug skill for complex problems

Bugs are inevitable. What matters is how quickly you can find and fix them. Claude Code is excellent at debugging because it can read your actual code, trace execution paths, and understand how components connect.

This lesson teaches you how to debug effectively with Claude Code. You will learn to share errors in ways that help Claude help you, let Claude investigate rather than guessing yourself, and fix underlying problems rather than patching symptoms.

Good debugging is about providing context and letting Claude explore. The more information you give, the faster Claude finds the problem.

When something breaks, start by sharing the error with Claude.

Copy the full error:

Include:

The error message itself

The stack trace if available

The command or action that triggered it

Tell Claude how to reproduce:

Reproduction steps help Claude understand when and why the error occurs.

Share relevant context:

Context narrows down where to look.

After you share the error, let Claude trace through your code. Do not guess at the cause yourself.

Ask Claude to investigate:

Claude reads the files mentioned in the stack trace, follows the code path, and identifies where things go wrong.

Follow-up questions:

These questions help Claude dig deeper.

Ask for hypotheses:

Claude lists potential causes ranked by likelihood. You can investigate each one.

A common mistake is fixing symptoms rather than causes. Claude can help you find the real problem.

Ask for root cause analysis:

Example:

Symptom: A null check prevents a crash.

Root cause: Data is not being loaded correctly upstream.

The symptom fix adds a null check everywhere. The root cause fix ensures data loads correctly so null checks are unnecessary.

Verify the fix:

Claude makes the fix, then runs tests or performs verification to confirm the problem is solved.

For complex debugging, use the built-in /debug skill:

This skill:

Enables debug logging for the session

Reads the session debug log

Analyzes the problem you described

Suggests investigation paths

The /debug skill is particularly useful when:

The problem is intermittent

Multiple components might be involved

You need detailed internal logs

After running /debug, Claude has access to detailed logging that helps trace what happened.

Different bugs need different approaches:

For runtime errors:

Share the error and stack trace. Claude traces back to the source.

For wrong behavior:

Describe what should happen versus what does happen.

For performance issues:

Describe the symptoms and when they occur.

For intermittent bugs:

Describe the pattern of when it happens and when it does not.

Fixing a bug is not complete until you verify the fix works.

Ask Claude to verify:

Claude makes the change, then runs tests or demonstrates that the bug is fixed.

Test edge cases:

Make sure the fix is complete, not just a quick patch.

Check for regressions:

A fix that breaks other things is not a fix.

Read the error carefully. Errors often tell you exactly what went wrong. Do not skip past them.

Start where it breaks. The stack trace points to where the error occurred. Start there and trace backward.

Check assumptions. Bugs often happen when something is not what you assumed. Check that variables have the values you expect.

Isolate the problem. Can you reproduce it with minimal code? Simplifying helps find the cause.

Compare to working code. If it worked before, what changed? Git diff between working and broken states.

Share full error messages and stack traces with Claude

Include reproduction steps and relevant context

Let Claude investigate rather than guessing at causes

Fix root causes, not just symptoms

Use /debug for complex problems requiring detailed logging

Verify fixes with tests and edge case checks

A bug is not fixed until verification passes

Practice debugging with these steps:

Find a bug in your project (or introduce one temporarily).

Copy the error message and share it with Claude.

Tell Claude how to reproduce the error.

Ask Claude to investigate and explain what's causing it.

Ask Claude to fix the bug.

Ask Claude to verify the fix works.

Run your tests to confirm nothing else broke.

This exercise builds your debugging workflow with Claude Code.

https://code.claude.com/docs/en/common-workflows - Debugging workflows and error sharing

https://code.claude.com/docs/en/best-practices - Root cause analysis and verification

https://code.claude.com/docs/en/skills - The /debug bundled skill