{
  "$schema": "robofaults-fault-record/v0",
  "kind": "error",
  "brand": "roomba",
  "page_en": "https://robofaults.com/roomba/error-21/",
  "page_es": "https://robofaults.com/es/roomba/error-21/",
  "code": "21",
  "slug": "error-21",
  "device_type": "vacuum",
  "name_en": "Internal communication error",
  "name_es": "Error de comunicación interna",
  "badge": "ERR 21",
  "severity": "warn",
  "severity_note_en": "mission stops; usually clears with a restart or reboot",
  "severity_note_es": "la misión se detiene; suele resolverse con un reinicio",
  "series": [
    "i",
    "j",
    "s"
  ],
  "tools_en": "none",
  "tools_es": "ninguna",
  "time_min": 5,
  "difficulty": "easy",
  "safety": "none",
  "safety_note_en": "",
  "safety_note_es": "",
  "meaning_en": "Error 21 means an <b>internal communication error</b> — one of the robot's boards stopped answering. Press CLEAN to retry. If it comes back, reboot. Error 21 that survives a reboot needs iRobot support, not parts.",
  "meaning_es": "El error 21 significa un <b>error de comunicación interna</b> — una de las placas del robot dejó de responder. Pulsa CLEAN para reintentar. Si reaparece, reinicia. Un error 21 que sobrevive al reinicio necesita al soporte de iRobot, no piezas.",
  "causes": [
    {
      "title_en": "Momentary firmware fault",
      "title_es": "Fallo puntual del firmware",
      "detail_en": "A hung internal process drops communication once and never again.",
      "detail_es": "Un proceso interno colgado corta la comunicación una vez y no vuelve a pasar.",
      "likelihood": "most_common"
    },
    {
      "title_en": "Board-level hardware fault",
      "title_es": "Avería de hardware en la placa",
      "detail_en": "Repeated error 21 after reboots points at a failing electronic component inside.",
      "detail_es": "Un error 21 repetido tras varios reinicios apunta a un componente electrónico interno que falla.",
      "likelihood": "uncommon"
    }
  ],
  "steps": [
    {
      "title_en": "Press CLEAN to retry",
      "title_es": "Pulsa CLEAN para reintentar",
      "detail_en": "Most occurrences are one-offs. Restart the mission and watch whether it completes.",
      "detail_es": "La mayoría de los casos son puntuales. Reanuda la misión y comprueba si termina."
    },
    {
      "title_en": "Reboot the robot",
      "title_es": "Reinicia el robot",
      "detail_en": "Hold CLEAN until the light ring swirls, then let it boot fully before testing again.",
      "detail_es": "Mantén pulsado CLEAN hasta que el anillo de luz gire y deja que arranque del todo antes de probar."
    },
    {
      "title_en": "Contact iRobot support",
      "title_es": "Contacta con el soporte de iRobot",
      "detail_en": "If error 21 persists after a reboot, the fault is internal. Note your robot's serial number before calling.",
      "detail_es": "Si el error 21 persiste tras el reinicio, la avería es interna. Anota el número de serie antes de llamar."
    }
  ],
  "parts": [],
  "related": [
    "15",
    "31"
  ],
  "sources": [
    {
      "label_en": "iRobot Support — i Series, Error 21",
      "label_es": "Soporte de iRobot — Serie i, error 21",
      "url": "https://homesupport.irobot.com/s/article/2413",
      "kind": "official"
    },
    {
      "label_en": "iRobot Support — j Series, Error 21",
      "label_es": "Soporte de iRobot — Serie j, error 21",
      "url": "https://homesupport.irobot.com/s/article/31097",
      "kind": "official"
    }
  ],
  "confidence": "official",
  "last_verified": "2026-07-05"
}