Social media giant Facebook was left embarrassed after its new 16 billion US dollars (£9.58 billion) acquisition, WhatsApp, went down for over two hours.
The team behind the instant messaging app, which was snapped up by Facebook on Thursday, apologised to its more than more than 450 million monthly global users after suffering "server issues".
The highly popular mobile phone applications's chat conversations showed a loading asterisk and the alert "Connecting..." while the problems persisted.
WhatsApp used its @wa_status account to tweet at 8:16pm UK time: "Sorry we currently experiencing server issues. We hope to be back up and recovered shortly.
At 10.48pm it announced the problems had been fixed, tweeting: "WhatsApp service has been restored. We are so sorry for the downtime..."
Some users complained about the problems, while others joked that the WhatsApp team had gone on holiday following their multi-billion dollar deal with Facebook.
Olympic medal-winning diver Tom Daley asked his 2.62 million Twitter followers: "Anyone else's WhatsApp stopped working?"
Software engineer Chris Sedlmayr (@catchamonkey) tweeted: "Anything that can 'go down' shouldn't be relied on. Plenty of decentralised ways to message, they can't go down as such".
Mathew Ingram (@mathewi) said: "WhatsApp undergoes some downtime, as founders are too busy counting out their Facebook billions one bill at a time".
Facebook announced on Thursday that its deal with WhatsApp comprised four billion US dollars (£2.4 billion) in cash and 12 billion US dollars (£7.18 billion) worth of Facebook shares.
The agreement also provides for an additional three billion US dollars (£1.8 billion) in restricted stock units to be granted to WhatsApp's founders and employees to be paid in four years.
Around 70% of WhatsApp's monthly 450 million users use the application every day, Facebook said.
Mark Zuckerberg, founder and chief executive of Facebook, said: "WhatsApp is on a path to connect one billion people. The services that reach that milestone are all incredibly valuable."
Jan Koum, co-founder and chief executive of WhatsApp, said: "WhatsApp's extremely high user engagement and rapid growth are driven by the simple, powerful and instantaneous messaging capabilities we provide.
"We're excited and honoured to partner with Mark and Facebook as we continue to bring our product to more people around the world."
The WhatsApp brand is to be maintained, and its headquarters will remain in Mountain View, California.
Mr Koum will join Facebook's board of directors, and WhatsApp's core messaging product and Facebook's existing Messenger app will continue to operate as stand alone applications.
The new move from Facebook comes after it recently reported record revenues of 2.5 billion dollars (£1.5 billion) from 750 million daily users.
The end of quarter results, published at the end of last month, showed a revenue rise of one billion dollars (£0.6bn) on the same period last year.
A total of 757 million people used the world's biggest social media platform every day between October and December, up from 618 million the same time in 2012.
In 2012, Facebook bought photo sharing social media site Instagram for one billion US dollars (£600 million).