Harry Styles fans were left frustrated after a rush to snap up presale tickets to his tour caused Ticketmaster to crash.
But there was "unprecedented demand" for the tickets and fed up fans said they were plagued by freezing and error messages.
"So far 4 hours of queues and multiple website crashes," one person posted on Twitter.
"I was at the front of the queue when the website went down and all I want to do is surprise my younger sister with tickets to see her favourite - devastated," said another.
One upset fan posted: "I'm crying in college right now."
Another said: "So at 09:02 I was happily sat at 112th in the queue and then BAM it crashed and I’m now 30490th in the queue, and 40 mins later I’ve barely moved. Fuming is an understatement right now."
Ticketmaster posted a message on Twitter saying they were doing what they could.
It said: "It seems @Harry_Styles has exceeded everyone’s expectations and ticket outlets are currently down under unprecedented demand. We're working hard to rectify issues and will keep updating you here as we work to get things back up and running."
They later followed up to say the site was working again.
Styles, 27, hits the road in June, kicking off in Glasgow on 11 June and then heading to Manchester and on to London's Wembley Stadium.
Read More: Olivia Wilde talks Harry Styles romance
Announcing the news last week, the singer posted on Instagram: "I’m so excited to see you. Thank you, I love you. H."
The general ticket sale starts on Friday, 28 January.
Watch: Harry Styles 'prepared to spend up to £10m' on property in Cornwall