Television channels, banks, GPs and supermarkets around the world have been rocked by the chaos - as schools all over Britain break up for the summer holidays today.
Meanwhile, schoolcomms - a communication app used by over 3,000 schools - says it is among the many companies affected by the outage.
Major railways and supermarkets were also badly hit by the IT outage.
Cybersecurity software firm CrowdStrike say they have identified the issue behind the global outage as a flawed anti-viral update.
The firm is reportedly used by Microsoft to handle various updates to their systems.
In a statement on social media, CrowdStrike said the global IT outage was “not a security incident or cyberattack”, adding: “The issue has been identified, isolated and a fix has been deployed”
However, cybersecurity experts claim it could be days before the disruption ends.
Researcher Kevin Beaumont said: "As systems no longer start, impacted systems will need to be started in ‘Safe Mode’, to remove the faulty update.
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"This is incredibly time-consuming and will take organisations days to do at scale. Essentially we have one of the world’s highest impact IT incidents caused by a cyber-security vendor."
Schools across Britain are in carnage today as a result of the IT failure.
Fuming parents have shared on social media how the schoolcomms shutdown prevented them from adding money to their kids' accounts for school meals and drinks.
"Last day of term and I can’t add money to my sons account as neither of @Schoolcomms app and website are not working. And ideas how he can buy a drink?", penned one mum.
Another wrote on X: "So thanks to the global IT outage, we have no Schoolcomms and we are all watching the news feeds in IT Support to see if any future quirks/blips are related to it.
"And here was me hoping for a calm and quiet day after this manic week."
Meanwhile, the UK health sector has also been hit, with NHS GP surgeries now unable to access patient records or book appointments.
Practices have taken to social media to report they cannot access the EMIS Web system.
EMIS Web is the most widely used clinical system for primary care in the UK.
Meanwhile, the National Pharmacy Association (NPA) also confirmed the IT outage is disrupting community pharmacies.
The Wilmslow Health Centre in Cheshire wrote on X: "All practices in the UK using the NHS-commissioned GP computer system EMIS are currently without access to their IT systems.
"This is beyond the control of GP surgeries. Please bear with us until we have our IT systems back online."
Global services affected by IT outage
Trains
Govia Thameslink Railway (GTR) - urged passengers to expect disruption due to "widespread IT issues"
Gatwick Express - warned travellers they are "currently experiencing widespread IT issues"
South Western Railway - all ticket vending machines are currently non operational - buy tickets online
National Rail - some train operators are unable to access driver diagrams at certain locations, leading to potential short-notice train cancellations
TransPennine Express - some TPE stations and systems are having IT issues - buy tickets online
New York City's MTA system affected
Washington D.C Metro trains - delayed
Airports and airlines
Manchester Airport - delays for those checking-in for Swissport flights
London Gatwick - passengers may experience some delays while checking in and passing through security but should still arrive for their normal check-in time
Ryanair - advise passengers to arrive at the airport three hours in advance of their flight to avoid any disruptions
Edinburgh Airport - wait times longer than usual
Stansted Airport - some airline check-in services reverted to being done manually, but main operational systems are unaffected and flights are still operating as normal
Luton Airport - running manual systems
Heathrow Airport - affected but flights operational - check with airline on latest journey information
Bristol Airport - flights cancelled to Amsterdam
American Airlines - all flights cancelled
United and Delta - no flights taking off
Allegiant Air and Spirit Airlines - flights grounded
Frontier and SunCountry - affected by outage
San Francisco Airport - passengers reporting suspended flights
Detroit Metro Airport - travellers sharing chaotic scenes of queues continuing to grow
Mumbai Airport - check-in desks shut down for IndiGo, Akasa and Spice Jet flights
Australian airline Qantas - flights grounded
Schipol Airport in Amsterdam - flights to and from the Netherlands affected
Spanish airport association AENA - reported issues at 42 airports
Rome's Fiumicino Airport affected
Ibiza Airport - empty due to IT outage
Hamburg Airport in Germany affected
BER Berlin Airport - Long queues
The Hague Airport in Rotterdam - travellers experiencing longer wait times
Narita International Airport in Narita, east of Tokyo - check-in delays
Palma Mallorca Airport affected
Suvarnabhumi Airport in Bangkok - longer queues reported
Hong Kong Express Airways passengers delayed at Hong Kong International Airport
Television Networks
Sky News - Friday morning breakfast show unable to air but now back on screens with reporter reading from printed notes
Paramount Global channels including MTV, VH1, CMT and Pop TV - bumped offline.
Britain's GPs
The Wilmslow Health Centre in Cheshire - without access to their IT systems
Solihull Healthcare Partnership in the West Midlands - affected ability to book/consult with patients this morning
Central Lakes Medical Group in Ambleside - stated there has been a "big effect" and delays on the phone expected
Pocklington Group Practice in the East Riding of Yorkshire - appointments needing to be cancelled and rearranged
Hulme Hall Medical Group, in Stockport - unable to offer any appointments
Windrush Medical Practice in Witney, Oxfordshire - continuing as normal for urgent enquiries but ask for routine concerns to wait until Monday
Grimethorpe Surgery in Barnsley - no access to the clinical system, EMIS Web
The National Pharmacy Association (NPA) confirmed the IT outage is disrupting community pharmacies
A surgery in Putney, southwest London - Displaying an error message online to patients who attempt to book
Global hospitals
Two German hospitals have been forced to cancel emergency operations
The hospitals, in the northern German cities of Luebeck and Kiel, cancelled all elective operations scheduled for today
Supermarketsand restaurants
Morrisons are affected
Some Waitrose and Co-op are now cash only
Gails and Waterstones experiencing some issues
Wetherspoons pubs - only accepting cash
Woolworths and Coles supermarkets in Australia - self service machines not working
Events
Manchester United ticket release postponed - morning’s ticket release will be postponed until midday and website will remain unavailable
Banks and supermarkets in Australia including Beyond Bank Australia have also been experiencing issues this morning.
Various Microsoft services in Japan and New Zealand are also battling tech issues
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What has been dubbed the 'blue screen of death' flashed across Microsoft screens around the world this morning
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Holidaymakers waiting in long lines at Stansted Airport
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Passengers were being handed bottled water at the London Airport amid delays
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Chaos at London Gatwick this morning
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The airport reported it was affected by the IT outage this morning
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Commuters are seen attempting to purchase train tickets from a self-service machine at Waterloo Station