Roborock · Robot Vacuum Moderate

Error 21 — LDS / laser sensor obstructed (top cover blocked)

On models with a vertical LiDAR, the rotating turret is blocked by an object on top of the robot or by the robot being pinned under furniture pressing down on the turret.

Keep using it?
Yes, with caution
DIY difficulty
Easy
Verified against
us.roborock.com ↗

How to fix it

  1. Free the robot from any furniture pinning the LiDAR.
  2. Remove any objects sitting on top of the robot.
  3. Spin the LiDAR turret by hand to confirm it moves freely.
  4. Add a no-go zone or use the included LiDAR-clearance bumper if available.
  5. Restart cleaning.

Why it happens

Typical signs: Voice prompt 'Laser distance sensor is jammed' · App shows Error 21 · Robot stops mid-clean · Found under low table

  • Robot wedged under low furniture LiDAR turret can't rotate because furniture pins it.
  • Object on top of robot Pet toy or cloth landed on top of robot.
  • Hair on turret base Same cause as Error 1 — hair seizes the spinner.

More Roborock robot vacuum codes

Error 1 Error 1 — LDS laser distance sensor blocked or stuck Error 10 Error 10 — Filter blocked Error 11 Error 11 — Magnetic strip / no-go interference Error 12 Error 12 — Battery low, returning to dock Error 13 Error 13 — Charging error / contacts dirty Error 14 Error 14 — Battery error

All Roborock codes → All robot vacuum codes →

Frequently asked questions

What does the Error 21 code mean on a Roborock robot vacuum?

On models with a vertical LiDAR, the rotating turret is blocked by an object on top of the robot or by the robot being pinned under furniture pressing down on the turret.

What causes the Error 21 code on a Roborock robot vacuum?

Robot wedged under low furniture: LiDAR turret can't rotate because furniture pins it. Object on top of robot: Pet toy or cloth landed on top of robot. Hair on turret base: Same cause as Error 1 — hair seizes the spinner.

Is it safe to keep using a Roborock robot vacuum with a Error 21 error?

Yes, with caution. This is rated a moderate-severity fault.

How do I fix Error 21 on a Roborock robot vacuum?

Free the robot from any furniture pinning the LiDAR. Remove any objects sitting on top of the robot. Spin the LiDAR turret by hand to confirm it moves freely.

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: us.roborock.com.