For more than a month, Jaguar Land Rover hasn’t built a single car.

The company, Britain’s largest automaker, shut down its systems on Sept. 1 after discovering a cyberattack, halting production at its factories in England, as well as sites in Brazil, China, India and Slovakia.

The production halt has probably cost the company millions of pounds a day. Jaguar Land Rover has not confirmed the nature of the attack, though cybersecurity experts say it was most likely an extortion-based attack, in which hackers steal data or block systems until a ransom is paid.

For companies and governments worldwide, defending their digital operations is a constant challenge. Cyberattacks seem inevitable lately, and large-scale theft of customer data has begun to feel almost routine. Attacks that upend company operations are exposing troubling vulnerabilities.

Few places have felt this more sharply in recent months than Britain. Three of the country’s biggest brands — the retailer Marks & Spencer, the supermarket chain Co-op, and Jaguar Land Rover — were all severely disrupted by cyberattacks this year, bringing pain to the lives of customers, workers, suppliers and government officials.

“It is happening elsewhere. It’s just Britain is having a pretty bad run of it,” said Ciaran Martin, the former chief executive of the National Cyber Security Center, part of the government’s intelligence and security agency, and a professor at Oxford.

What stands out is the scale of the disruption. Jaguar Land Rover, which is owned by the Indian conglomerate Tata Group, employs 34,000 people in Britain and supports another 120,000 British jobs through its supply chain. The automaker operates a just-in-time manufacturing process, so parts arrive when they are needed. When the company halted production, it also stopped payments to suppliers, some of which have since begun cutting staff hours or laying off workers.