Microsoft said on Saturday that the CrowdStrike update had affected 8.5m Windows devices. This was less than 1pc of all machines operating the software, but had major impacts because CrowdStrike is widely used in businesses.
The faulty update caused a blue error screen on many computer screens, rendering them unusable until they were fixed.
CrowdStrike said on Monday that “a significant number” of the affected computers were back online and apologised for the disruption.
Figures from data company OAG showed that 9,650 flights had been cancelled between Friday and Sunday. While many airlines had recovered, 2,619 flights were cancelled on Sunday, with US airline Delta accounting for most of those.
The NHS said that its systems were back online but that “there still may be some delays as services recover”.
The European Commission pursued Microsoft in the early 2000s over concerns that the company’s popular Windows software gave it an unfair advantage in other areas such as web browsers.
In 2009 the company agreed to boost choice for computer users in browsers and other software.
It comes as new European laws are forcing Apple to open up its iPhone. Under the new Digital Markets Act, the company will have to allow alternative app stores and web browser engines on the iPhone.
Apple has claimed the changes will make the iPhone less safe.