Robot vacuum occasionally fails to detect stairs and has nearly fallen or actually fallen once.

Safety first: Immediately stop using the robot near stairs until the issue is resolved. Use physical barriers to block stair edges.

Steps to try:

• 1. Clean cliff sensors: Wipe all underside cliff sensor windows with a soft, dry cloth.
• 2. Improve contrast: If the floor at the top of the stairs is very dark or patterned, place a light‑colored rug a short distance from the edge and set a no‑go zone if supported.
• 3. Test carefully: With the robot supervised, run it near the stairs and be ready to catch it. Confirm that it stops before the edge.
• 4. Service if unreliable: If the robot still approaches edges too closely, have the cliff sensor module inspected and replaced by a technician.