Some internet users were unable to search using Yahoo or Microsoft over the weekend after a snippet of bad code brought services to a standstill.
Reuters quoted an inside source who claimed that a problem at Microsoft rolled onto the Yahoo service and left a lot of people unable to perform searches.
The source told the news agency that a rollback procedure that Microsoft has in place failed, and that the companies were forced to go through their server estate, shutting down hardware until everything went back to normal.
Microsoft told Reuters that there was a problem over the weekend which has since been rectified.
"This morning, some of our customers experienced a brief, isolated services interruption which has now been resolved," the firm said.
All services have now been restored, and searches are back to usual. It appears that Bing was restored first, and that Yahoo followed after. Yahoo search seems to have been unavailable for about four hours.
Microsoft has provided Yahoo with Bing search since 2009, and Yahoo is the de facto search engine on the Mozilla browser in the US having previously used Googel for many years.
Security blogger Graham Cluley suggested that the problems won't have affected many people.
"There was an outage of Microsoft's search engine, Bing, earlier in the day, and Yahoo depends on that technology for its own search infrastructure.
"It's fair enough that you wouldn't have noticed if Bing had gone down. After all, there are probably even less people using Bing than plonkers still clinging desperately onto their Google Glasses."
The fact the outage was not caused by a cyber attack and was instead an internal error will probably have been some relief to Microsoft and Yahoo, given the recent spat of incidents that have affected firms, notably Sony.
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