Uber has been stripped of its London license.
Regulators said a 'pattern of failures' made it unfit to operate in the city.
One particular danger was cited.
A change to Uber systems allowed unauthorized drivers to upload their photos to other drivers' profiles.
That meant they could pick up passengers as if they were the booked driver.
Transport for London says that happened about 14 thousand times.
Uber called the decision 'extraordinary and wrong'.
It says it's addressed all such issues since an original decision to strip it of a license in 2017.
It's been on a probationary license since a subsequent judicial ruling.
Now it plans to appeal, and can continue to operate during that time.
The resulting court action could drag on for months.
For Uber there's a lot at stake.
London is one of its biggest markets.
For Londoners it could mean finding a new cab.
Rival ride-hailing apps like Bolt and Kapten are already expanding aggressively in the city.
Drivers of the famous black taxis will also be hoping to claw back some trade.