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The Sendmux API uses standard HTTP status codes and returns a consistent error envelope so you can handle failures programmatically.

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Error response format

{
  "ok": false,
  "error": {
    "code": "invalid_parameter",
    "message": "A human-readable description of the error.",
    "param": "from_date",
    "doc_url": "https://docs.sendmux.ai/api-reference/errors#invalid_parameter"
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}
The param field is only present when the error relates to a specific request parameter. Always include request_id when contacting support.

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Error codes

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authentication_required

HTTP 401 — The request has no Authorization header or the API key is invalid, expired, or revoked. 
# Fix: include a valid API key
curl https://app.sendmux.ai/api/v1/providers \
  -H "Authorization: Bearer smx_root_your_key_here"

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insufficient_permissions

HTTP 403 — The API key is valid but lacks the required permission for this endpoint. Check the permission table to see which permission each endpoint requires.

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invalid_parameter

HTTP 400 — A query parameter has an invalid format or value. The param field identifies which parameter is at fault.

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missing_parameter

HTTP 400 — A required query parameter is missing from the request.

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not_found

HTTP 404 — The requested resource does not exist, or it belongs to a different team than the one associated with your API key.

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rate_limit_exceeded

HTTP 429 — You have exceeded the rate limit of 600 requests per minute. Wait for the duration specified in the Retry-After header before retrying.

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internal_error

HTTP 500 — An unexpected server error occurred. If this persists, contact support with the request_id from the response.