An explicit authentication failure is more specific than a general launch failure — it means the sign-in step itself is the problem, not the install or environment. Three real causes cover almost every case.
Sessions don't stay valid forever, and a stale one can fail silently instead of showing a clear "please sign in again" message — it just looks like authentication broke for no reason.
A machine previously used by a different account, or with more than one account ever signed in, can end up with conflicting cached credentials that neither account can cleanly use.
The same network causes that block a general launch can specifically interrupt the authentication handshake — a VPN, a corporate firewall, or a captive portal network are the usual suspects.
The free guide covers the permission model and your first real workflow — the two things that actually matter once auth issues are resolved.
Get the Free Guide →Sometimes it's the same underlying cause, but an explicit authentication error is more specific than a generic launch failure — it points directly at the sign-in step rather than the broader set of causes covered in the general troubleshooting guide.
No — signing out and back in resets the session/auth state, not your local project configuration, CLAUDE.md files, or settings.
Yes, more often — a shared machine or a machine used across multiple accounts is more likely to have a stale or conflicting session than a single-user setup.