Jersey GP surgeries, financial institutions and schools are among the organisations affected by a worldwide IT outage.
It is thought the issue has been caused by a faulty update to CrowdStrike, a cybersecurity service for Windows PCs.
The outage has grounded flights around the world and taken TV channels off air, including Sky News.
In Jersey, Butterfield bank has advised customers its services are down, and some GP appointments have had to be rescheduled.
Despite this, patients are being asked to attend as normal unless told otherwise.
We are aware of IT issues, GPs have asked us to communicate that they would like patients to attend as normal. The hospital remains open. @GovJersey
— Jersey Gov Health & Community Services (HCS) (@GovJsyHCS) July 19, 2024
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Jersey's hospital and other public services from Customer and Local Services both remain open, although schools' electronic student registers were affected.
Some retailers including B&Q and Waitrose have had issues with their tills and taking contactless payments.
Ports of Jersey has confirmed no flights or ferries have so far been affected.
In a statement, the operator said: "No flights have yet been affected in Jersey, but a knock-on effect on inbound flights is possible as some airports are manually checking paper boarding cards.
"We're continuing to monitor any impact on inbound flights, and have updated digital screens around the airport with information. Harbour operations are unaffected."
World Duty Free has now re-opened and is accepting cash-only, after being closed for a time this morning, 19 July.
The island's Chief Minister, Deputy Lyndon Farnham, has confirmed that work is ongoing to investigate the issue and its impact locally.
In a post on social media, Deputy Farnham wrote: "Islanders may be aware of the global IT issues being reported in the media today.
"Officials are currently investigating what impact may be felt here in Jersey and regular updates will be provided throughout the day as information emerges.”
Global IT outage update: Officials are working establish what impact might be felt here in Jersey. Further updates will be provided during the day as details emerge from our incident management process.
— Dep. Lyndon Farnham (@lyndonfarnham) July 19, 2024
CrowdStrike, the software provider which distributed the update which caused the widespread outage to Windows PCs, confirmed the incident is "not a cyber attack".