Tens of thousands of people were disappointed when they tried to get tickets for an audience with Michelle Obama at London's Royal Festival Hall.
Many in the social media have indicated that more than 40,000 people are in the queue for tickets.
Former US First Lady will perform in the 2,900 seat hall on 3 December.
There are tickets for thousands of pounds on Viagogo, but the venue said they were asked to remove them.
Any tickets purchased by unauthorized third parties are not permitted.
Obama will discuss her memoir, Becoming, with award-winning writer Chimamanda Ngozi Adichie.
They will talk about their childhood experiences, their work, motherhood and "their time at the most famous address in the world".
- Michelle Obama dances with Parker, the portrait girl
She will also share "Learning Lessons of Life," hoping to "inspire people to become the very best version of themselves."
People tweeted that they had been queuing up at the venue since 4am.
The South Bank Center, a multi-arts venue adjacent to the Thames, tweeted at 10:30 GMT to say they were sold out.
People got up at 4am for Michelle Obama's presale tickets. If you are serious, you have to get up early !!! Do not log in at 8 in the morning, do not come to the center of South Bank at 9 in the morning, you have no chance
– Abigail Kwakye (@Abigail_Kwakye) November 7, 2018
The date in London is in the middle of a 13-day tour that begins on November 13 in Obama's hometown of Chicago, where she will talk to Oprah Winfrey.
Tickets that were sold quickly in the US, and Obama has tweeted that she was "really humbled by the reaction to my upcoming book tour."
The South Bank Center said they are also in the process of identifying advertised tickets.
They told the BBC that due to the "extreme demand for this event, unfortunately, there will be people who are disappointed".
They said they had "been working hard to ensure that tickets are available to the widest possible audience by limiting the number of tickets to two per booker and ensuring that there is a lower price of £ 30."
Three hundred tickets were withheld to be made available free of charge to secondary school students in London and the UK and local charities.
The South Bank Center said that there are no exact figures of how many have tried to get tickets.
Part of the tickets were sold yesterday for the members of the venue, the rest was sold today at 10 clock to the general public.
follow us on Facebook, on twitter @ BBCNewsEntsor on Instagram bbcnewsents, If you have an email with a story suggestion email@example.com.