Claude Code exits immediately after launch with no output or error mes — Claude Code Certified Professional Practice — Claude Cert Academy

Claude Code exits immediately after launch with no output or error message. What is the first diagnostic step?

• Reinstall Claude Code with npm install -g --force
• Delete the ~/.claude directory and start fresh
• Verify that ANTHROPIC_API_KEY is set and non-empty in your shell environment
• Downgrade to a prior version of Claude Code

Answer: Verify that ANTHROPIC_API_KEY is set and non-empty in your shell environment

A missing or empty API key is the most common cause of silent immediate failures. Checking echo $ANTHROPIC_API_KEY should be the first step before more invasive debugging.

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