Error 21 Moderate Easy DIY

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

Roborock Robot Vacuum · Error code Error 21

What Error 21 Means

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.

Symptoms

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

Common Causes

1
Robot wedged under low furniture

LiDAR turret can't rotate because furniture pins it.

2
Object on top of robot

Pet toy or cloth landed on top of robot.

3
Hair on turret base

Same cause as Error 1 — hair seizes the spinner.

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.

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 →

Verified against manufacturer documentation: global.roborock.com

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.