Owners of Amazon's Ring smart doorbells have been reporting "phantom" visitors, with the bell chiming but no-one being at their door.
Amazon has blamed the issue on "infrastructure delays" - making real doorbell presses arrive later.
It said its "processing infrastructure was running behind", which caused delays in people receiving the notifications.
The issue was now resolved, it said, apologising for any inconvenience.
Amazon did not say how many people had been affected or what caused the delay, but users across the UK, Europe and US reported the random rings throughout the day on 30 September.
Some took to Twitter to describe how they were getting a succession of rings, with others saying their devices were going off every 10 minutes.
Others said that the phantom rings were unnerving, with children scared when the doorbell sounded and no-one was was there.
"Very unnerving for my elderly mother who lives alone," said one Twitter user.
In March, the BBC revealed that Amazon keeps records of every motion detected by its Ring doorbell, something privacy experts said gives its huge insights into customers' lives.
Ring, which makes home cameras as well as doorbells, has had security issues in the past.
In December 2019, a video shared on social media showed a hacker talking to a young girl in her bedroom via the family's Ring camera.
The hacker greeted the girl saying: "It's Santa. It's your best friend."
Earlier this week, Amazon revealed a flying camera that launches if sensors detect a potential break-in.