NHS England has warned of “continued disruption” to GP services into next week after Friday’s global IT outrage, as air passengers continued to face delays and flight cancellations. Passengers had their travel plans ruined on Friday as thousands of flights were cancelled internationally after a botched software upgrade hit Microsoft’s Windows operating system. The incident caused havoc worldwide across a number of services, with hospital appointments cancelled, payroll systems seizing up and TV channels going off air. GP practices in the UK said they could not see patient records or book appointments, and pharmacy services were also affected. The software update that caused global havoc came from the US cybersecurity company CrowdStrike, which left many Microsoft Windows users facing a “blue screen of death” as their computers failed to start. CrowdStrike’s chief executive, George Kurtz, said he was “deeply sorry” and made clear it was “not a security or cyber incident”. NHS England reported on Saturday afternoon that its systems were “coming back online in most areas” but “still running slightly slower than usual”. A spokesperson said: “As practices recover from the loss of IT systems on Friday, there may be some continued disruption, particularly to GP services, in some areas into next week as practices work to rebook appointments. “The advice for Monday remains that patients should attend appointments as normal unless told otherwise.” Microsoft estimates the CrowdStrike update has affected 8.5m windows devices, or less than 1% of all Windows machines, according to Reuters. Nick Kaye, the chair of the NPANational Pharmacy Association, which represents independent community pharmacies in the UK, said patients collecting prescriptions could still face disruption this weekend. “Systems are by and large back online and medicine deliveries have resumed in many community pharmacies today after the global IT outage,” he said. “However, yesterday’s outage will have caused backlogs and we expect services to continue to be disrupted this weekend as pharmacies recover.” Holidaymakers have been warned it could take weeks to recover. Nearly 7,000 flights were cancelled worldwide on Friday, including 408 to and from the UK. As of 10am on Saturday, 23 departing and 25 inbound flights had been cancelled in the UK, according to figures from the aviation analytics firm Cirium. Travellers at Heathrow and Gatwick experienced long queues on Saturday. Charles, 50, from the Midlands, said he was glad he was in a queue to leave the country rather than arriving to the UK. “I’m glad it’s because we’re going out,” he said. “It’d be different if we were going back.” The transport secretary, Louise Haigh, said on Saturday that IT systems at airports were “back up and working normally”. She said: “We are in constant communication with industry. There continues to be no known safety or security issues arising from the outage.” But she added: “Some delays and a small number of cancelled flights are expected today.” Doug Bannister, the chief executive of the Port of Dover, said hundreds of stranded air passengers had arrived in hope of taking a ferry instead. Bannister said the port was expecting more than 10,000 cars on Saturday, up from 8,000 the day before. “So far there is no congestion in the town of Dover. Approach roads are busy but moving. Everything is running well.” Train travellers were also affected. On Friday London Euston station was packed with hundreds of passengers after trains were delayed or cancelled. The issues persisted into Saturday morning. At London Waterloo, passengers were unable to buy tickets from machines at the station, while at Paddington, QR code scanners stopped working. Several US airlines and airports across Asia said they were resuming operations, with check-in services restored in Hong Kong, South Korea and Thailand, and mostly back to normal in India, Indonesia and at Singapore’s Changi airport as of Saturday afternoon. “The check-in systems have come back to normal [at Thailand’s five major airports],” the Airports of Thailand president, Keerati Kitmanawat, told reporters at Don Mueang airport in Bangkok. “There are no long queues at the airports as we experienced yesterday.” Atlanta airport, the busiest in the world by passenger traffic, said it had not been affected by the outage but was working with “airline partners” who were. While some airports halted all flights, airline staff in others resorted to manual check-ins for passengers. The US Federal Aviation Administration (FAA) initially ordered all flights to be grounded “regardless of destination”, although airlines later said they were re-establishing their services and working through the backlog. India’s largest airline, IndiGo, said operations had been resolved, in a statement posted on X. “While the outage has been resolved and our systems are back online, we are diligently working to resume normal operations, and we expect this process to extend into the weekend,” the carrier said on Saturday. A passenger told Agence France-Presse that the situation was returning to normal at Delhi airport with only slight delays in international flights. In Europe, major airports including Berlin, which had suspended all flights on Friday, said departures and arrivals were resuming.