Why does Claude Code keep saying the session expired?

This happens when your authentication token becomes invalid, expired, or corrupted. It can also be caused by macOS keychain locks, VPN interference, or OAuth callback timeouts.

How do I reconnect Claude Code?

The fastest way to reconnect is to sign out, clear your cached credentials using 'rm -rf ~/.claude/cache', and then complete the full login flow again.

What is an OAuth callback timeout?

It occurs when the browser takes longer than 60 seconds to pass the authentication token back to the CLI, often due to too many open tabs or a slow network connection.

Why does Claude Code say 'installation failed' but then 'installation complete'?

This contradictory message almost always means a stale lock file exists from a previous interrupted install. The installer aborts due to the lock but then partially completes a different step, giving you two contradictory status messages. Remove the lock file at ~/.local/state/claude/locks/ and reinstall.

I get claude: command not found even after a successful install. What's wrong?

Your terminal session hasn't loaded the updated PATH that the installer added to your shell config. Open a new terminal window, or run source ~/.zshrc (or ~/.bashrc on Linux). If that doesn't work, confirm that npm's global bin directory is actually in your PATH.

Do I need sudo to install Claude Code?

No — and using sudo will likely cause more problems. Set your npm global directory to a user-owned path with npm config set prefix ~/.npm-global, add that to your PATH, and then install without sudo.

Claude Code installation fails with a TLS/SSL error. How do I fix it?

This happens in corporate environments that use SSL inspection. Export your company's CA certificate path: export NODE_EXTRA_CA_CERTS=/path/to/ca.pem. Your IT team can provide the certificate file.

The Claude Code installer just hangs and never completes. What's happening?

A hanging installer almost always means a network block. The installer downloads from storage.googleapis.com. Set your proxy with export HTTPS_PROXY=http://your-proxy:port and retry, or ask IT to whitelist that domain.

I'm on Windows. Should I use npm or the curl installer?

Use PowerShell with npm install -g @anthropic-ai/claude-code. Don't use Git Bash; it lacks TTY support and will cause raw mode errors. If you're in WSL, use the curl installer within your Linux environment.

How do I know if Claude Code installed correctly?

Run claude --version to confirm the binary is accessible, then run claude doctor for a full diagnostic report. Both should return clean results with no errors before you start using the tool in a real project.