| 401 / UNAUTHENTICATED | Check the Bearer token and environment. Revoked tokens cannot be reused. |
| 422 / EMAIL_REQUIRED | Create a token through private Telegram and complete one-time email capture. Contact support if an existing-email account still fails. |
| 422 / INVALID_BUDGET | Use integer cents in the API and stay inside the current offer’s budget range. |
| Offer unavailable / OFFER_NOT_FOUND | Refresh inventory and review a new quote before paying. |
| Checkout expired (410) | Start a new checkout after checking that the previous one was not paid. |
| Checkout already completed (409) | Inspect the existing order/deployment; do not pay again. |
| 409 / PURCHASES_PAUSED | New purchases are temporarily paused. Wait until purchases resume before retrying checkout; do not loop purchase requests. Contact support if you need help. |
| 404 deployment/credentials | Check the deployment ID, account, state, and whether access is ready. |
| 503 / COMPUTE_TEMPORARILY_UNAVAILABLE | Wait and refresh inventory; do not loop purchases. |
| 500 / INTERNAL_ERROR | Save the request ID and time, contact support, and avoid blind purchase retries. |
| SSH connection refused/timeout | Confirm active state and the supplied host/port; provisioning or network setup may not be ready. |
| SSH permission denied | Use the supplied username and correct key/password; check key file permissions. |
| Missing email | Check junk mail and deployment status, then contact support with the order ID. |
| Jupyter unreachable | Check that it is running, the SSH tunnel is open, and the local port matches. |
