Apple has apologised for a 12-hour outage that left customers without access to some of its most popular online services, including the App Store and iTunes. The company said the fault was caused  an internal DNS [domain name system] error. The technical glitch meant that people were unable to download songs, books and apps and could have cost Apple in the region of $48 million. Sorry: Apple has apologised for a 12 hour outage that left users without access to some of its most popular online services, including the App Store and iTunes (pictured) Problems began yesterday just before 9am GMT and ended at around 8.30pm GMT. The fault affected customers of the App Store, iTunes, iBooks store and Mac App store in over 40 countries. Users of Apple's iCloud service were also unable to access emails and documents for around four hours and app developers were affected too as iTunes Connect and Testflight were down all day. An Apple spokesman suggested the problem was caused by the firm's own engineers. 'We apologise to our customers experiencing problems with iTunes and other services this morning,' he said. 'The cause was an internal DNS [domain name system] error at Apple. We're working to make all of the services available to customers as soon as possible, and we thank everyone for their patience.' Error: The fault affected customers of the App Store, iTunes, iBooks store and Mac App store in over 40 countries. This screenshot shows one message that greeted iTunes users . Red alert: Yesterday, Apple's status page was updated to show that customers couldn't access App Store, iTunes, iBooks store and Mac App store in over 40 countries (pictured). The problem has now been fixed . An Apple spokesman suggested the problem was caused by the firm's own engineers. 'We apologise to our customers experiencing problems with iTunes and other services this morning," he said. 'The cause was an internal DNS [domain name system] error at Apple. We're working to make all of the services available to customers as soon as possible, and we thank everyone for their patience.' A DNS error refers to a fault in system that matches a domain name to an IP address - a chain of numbers that's used to send and receive data. Yesterday, Apple confirmed in an update on its status page that the issue was global. A DNS error refers to a fault in  system that matches a domain name to  an IP address - a chain of numbers that's used to send and receive data. Yesterday, Apple  confirmed in an update on its status page that the issue was global. Users could see music, film and TV content is visible in the iTunes Store, but couldn't buy it. Some users saw error messages, while others were simply unable to download the goods they wanted to buy in the digital stores. The front pages of both the App Store and Mac App Store were accessible, but there were broken pages on the sites when accessing individual apps. Some customers were frustrated to see a spinning circle indicating that a song was in the process of being downloaded, but nothing happened. Frustration: In both iTunes and the App store, users saw see a spinning circle indicating that a song or app was in the process of being downloaded, but nothing happened, as shown in the screenshots above . In 2014 Apple revealed in that it had made $18.06 billion in revenue from iTunes, including its software and services, making up 10 per cent of Apple's total net sales. If this year's revenues match 2014's, the firm could have lost more than $2 million an hour - equivalent to $34,000 every minute. Seeing as the outage encompassed other services, it could follow that Apple's losses were much higher than this. Tim Cook has previously said that the App Store posted $4.6 billion in revenue for the fourth quarter of 2014, which means that firm could have lost around $2 million an hour, or almost $35,000 a minute. Based on those figures, yesterday's technical problem could have cost the company the region of $48 million. Others were shown an error page saying that content could not be displayed, or that the store was temporarily unavailable and could not complete their request, when they tried to download an album. An early post from Californian tech giant's Apple Support Twitter handle said: 'APP STORE ISSUE: You may be receiving an error this morning. Apple are currently working on this and we do apologise.' In 2014 Apple revealed that it had made $18.06 billion in revenue from iTunes, including its software and services, making up 10 per cent of Apple's total net sales. If this year's revenues match 2014's, the firm could have lost more than $2 million an hour  -equivalent to $34,000 every minute. London-based social media analyst Tim Grimes tweeted: 'Based on 2014 iTunes Revenue: Apple are losing $34,246 per minute, $2,054,794 per hour the #iTunes store is down.' Seeing as the outage encompassed other services, it could follow that Apple's losses were much higher than this. Tim Cook has previously said that the App Store posted $4.6 billion in revenue for the fourth quarter of 2014, which means that firm could have lost around $2 million an hour, or almost $35,000 a minute. Based on those figures, yesterday's technical problem could have cost the company in the region of $48 million. Yesterday, one person tweeted: 'If iTunes doesn't start working within the next two hours I will literally cry...' A user called MisterDanD said: ' iTunes, App Store is DOWN worldwide, which is screwing up my morning! has someone hacked them? #apple #iTunes' and a user called lightcap wrote: 'Apple's app store is down (for purchasing, not browsing), but the world's most useless site remains useless as ever...' posting a link to the company's status page. Making a humorous reference to Apple's new MacBook, which was unveiled with just one port earlier this week, Twitter user schwarztech said: 'Maybe someone accidentally unplugged the single USB-C cable that the App/iBook Store runs off of?' The App Store was last down on Monday, but the move was intentional as Apple prepared to launch its Apple Watch in San Francisco.
Users couldn't access the App Store and iTunes for 12 hours yesterday . Apple said the fault was caused an internal DNS error . Technical glitch may have cost the company around $48 million . An update on Apple's status page confirmed the problem was global .