In a message seen by the BBC, workers were told that the offices would reopen on Monday 21 November.
It did not give a reason for the move.
The announcement comes amid reports that large numbers of staff were quitting after new owner Elon Musk called on them to sign up for “long hours at high intensity” or leave.
The message went on to say: “Please continue to comply with company policy by refraining from discussing confidential company information on social media, with the press or elsewhere.”
The reports have been met with consternation from unions with Prospect, the union for tech workers, asking Twitter UK to meet regarding the treatment of its employees.
“We will not let these makings of a digital P&O pass unchecked,” said Mike Clancy, general secretary of Prospect, referring to the ferry operator’s decision to sack staff and replace them with agency workers earlier this year.
“We are urgently seeking a meeting with Twitter UK Ltd to discuss how it will manage its collective redundancy consultation, ensure a fair and transparent process, and meet its duty of care and legal obligations to employees, including those with particular needs.
“Prospect will continue to do everything we can to support our members at Twitter. Big tech barons are not above the law and we will hold Twitter to legal account where possible.”
‘Nobody left in chain of command’
There are signs that large numbers of workers have resigned because they have not accepted Mr Musk’s new terms.
One former Twitter employee, who wished to remain anonymous, told the BBC: “I think when the dust clears today, there’s probably going to be less than 2,000 people left.”
They claimed everyone in their team had been sacked.
“The manager of that team, his manager was terminated. And then that manager’s manager was terminated. The person above that was one of the execs terminated on the first day. So there’s nobody left in that chain of command.”
Another person said they had resigned even though they had been prepared to work long hours.
“I didn’t want to work for someone who threatened us over email multiple times about only ‘exceptional tweeps should work here’ when I was already working 60-70 hours weekly,” they said.
Twitter did not immediately respond to a request for comment from the BBC.
In response to staff leaving, former Twitter vice-president Bruce Daisley told the BBC there were former Twitter engineers claiming the social media platform could “fail as soon as Monday”.
“There’s a large number of features that really seem to be predicated on having engineers on site,” he said.
“If those engineers have gone, then it does threaten the sustainability of the product.
“So, there’s a lot of people posting where else you can find them online.”
This week, Mr Musk told Twitter staff that they had to commit to working long hours and would “need to be extremely hardcore” or leave the company.
In an email to staff, the firm’s new owner said workers should agree to the pledge if they wanted to stay, the Washington Post reported.
Those who did not sign up by Thursday 17 November would be given three months’ severance pay, Mr Musk said.
Earlier this month the company said that it was cutting about 50% of its workforce.
Employees have been tweeting using the hashtag #LoveWhereYouWorked and a saluting emoji to show they were leaving the firm.
Despite the turmoil at the company, Mr Musk tweeted on Friday: “And… we just hit another all-time high in Twitter usage lol.”
Satirist Frank Lesser replied: “‘Rome has never been this brightly lit at night!’ – Nero” – a reference to the Roman emperor who is reputed to have fiddled while Rome burned.
Before Mr Musk took control of Twitter the company had about 7,500 staff. The firm was also reported to have employed thousands of contract workers, the majority of whom are understood to have been laid off.
The world’s richest person became Twitter’s chief executive after buying the firm last month in a $44bn (£37bn) deal.
Mr Musk seemed unconcerned about reports that Twitter was on the brink of shutting down, tweeting: “The best people are staying, so I’m not super worried”.
In separate posts he tweeted a skull and crossbones emoji and a meme showing a gravestone with the Twitter logo on it.
Is this really the end of Twitter?
Staff have been leaving in their droves – half the workforce was laid off by Mr Musk one week after he completed his purchase of the platform, and many more are choosing to leave since he sent an email demanding “hardcore” working conditions and long hours from his remaining employees.
Quite a few of those departing, according to their Twitter bios, are engineers, developers and coders – the people who work on the guts of what makes Twitter function.
Let’s take the two biggest vulnerabilities that could knock the blue bird off its perch very swiftly.
Could it be hacked?
The first and most obvious would be a catastrophic hack.
Twitter, like all big websites (including this one, the BBC), will be constantly under attack from bad actors – even at state level – wanting to cause mischief. World leaders, politicians and celebrities all have personal Twitter accounts with millions of followers – a low-hanging fruit for a hacker wanting a lot of people to see their scam, as we have seen before.
Or they might just want it to disappear, so they bombard it with web traffic to see if it gets overwhelmed and shuts down that way. Attempts like this will be happening all the time – it’s a constant battle.
Cyber-security is, or at least should be, an important part of any 21st Century company’s day-to-day operations. Last week Twitter’s head of cyber-security, Lea Kissner, left the company. It’s not known if she was replaced. (Twitter also has no communications team, so there’s no easy way to ask.)
Twitter’s security is likely to be pretty robust. You can’t run a site used by 300 million people every month that’s held together with a bit of string. But that robustness requires continuing maintenance.
Think about your own phone, or laptop, and the regular security updates you have to install. That’s because new vulnerabilities are regularly unearthed, new chinks in the armour that you didn’t know you had, and it’s the job of the provider to send you the fix.
Servers under threat
The second potential disaster is that the servers are knocked out – either by someone with a grudge, or by mistake during a routine bit of maintenance that’s not properly supervised.
Without servers, there is no Twitter (or Facebook, or Instagram or indeed our digital world.)
Servers – powerful computers – are like the physical bodies of these platforms. They exist in data centres. These are effectively warehouses full of computer servers which are central to the operations of online businesses. The world runs on servers.
As you can imagine, all of those machines generate a lot of heat. Data centres have to be kept cool, and they require a constant source of electricity.
The servers themselves also require maintenance and replacement, as data gets migrated between them. All of that has the capacity for something to go wrong. It would be sudden and dramatic if it did.
The nuclear option
Elon Musk knows all this, of course. Let’s not assume that he doesn’t. However he may choose to play the buffoon.
We don’t know who is currently keeping watch.
But something happened to me yesterday that made me think perhaps there are more people at Twitter watching than we think.
I told the story about an astronomer who was locked out of her account after wrongly falling foul of automated moderation tools. Nobody at Twitter or Mr Musk’s other firms responded to me, or made contact with her. But her account was indeed restored later that day.
Somebody, somewhere inside Twitter, was paying attention. Perhaps there are still enough of them who are doing just that.
There is of course a third option – the nuclear one – which is that Musk declares Twitter bankrupt, and it gets wound down. Although right now he seems to be enjoying his status as Chief Twit.
How to download your tweets in case Twitter shuts down permanently
Twitter is in a precarious situation amid growing questions about the site’s ability to continue operating. Hundreds of employees have reportedly opted to quit after the ultimatum that Elon Musk issued to the staff Wednesday.
The number of engineers overseeing multiple critical systems had been reduced, in some cases to near zero, according to people familiar with the situation who spoke to The Washington Post, and hashtags including #RIPTwitter, #TwitterDown and #Goodbye have been trending.
Some Twitter users — including politicians, embassies and government departments — have started preparing for the worst in case the site goes down permanently.
Is Twitter shutting down?
Probably not (right now). In public comments, owner Elon Musk continues to express confidence. Overnight, he said the company had “just hit another all-time high in Twitter usage” — a high presumably related to the number of people tweeting about Twitter.
“The best people are staying, so I’m not super worried,” Musk wrote Thursday about his employees. Remember, Musk paid $44 billion for Twitter, so he has a big incentive to prevent its collapse.
The fears that Twitter could go down are linked to the current staffing crisis — people familiar with the situation say that many engineers working on critical systems have left, leaving the system vulnerable to problems and with few people left to fix them.
The departures also are said to have had a major impact on teams working on misinformation and fake accounts, which could lead to an increase in online harassment or dangers for activists and others who use the site to share sensitive information.
Some users have been reporting functionality problems with Twitter, according to Downdetector.com, which indicated that thousands of Twitter outages had been reported in the last 24 hours.
Why are Twitter employees quitting?
Musk has owned the company for less than a month, and staffing levels have fallen sharply.
Roughly half the staff was cut in an initial round of layoffs this month. That was followed by Musk’s announcement last week that all workers would be required to return to the office, angering many of the remaining staffers.
Then, on Wednesday, Musk issued an ultimatum to the remaining employees, telling them to commit to a new “hardcore” Twitter or leave the company with severance pay; that ultimatum expired at 5 p.m. Eastern time Thursday. Hundreds of Twitter employees opted to take severance instead of staying, current and former employees said.
Musk has since appeared to backtrack on the return-to-office mandate — in what is seen as a sign that the number of those declining to sign was greater than anticipated.
It’s not clear how many Twitter employees are remaining.
How do I download or backup my tweets?
If you’re worried about Twitter going down, you can start by downloading all of your old tweets.
Twitter offers a backup option, however it in the past week there have been reports that the files are delayed or not sent to users at all. In the past, Twitter said it can take 24 hours or longer for your data to be readyGo ahead and put in a request to be safe.
Go to Settings → Your Account → Download an Archive of Your Data. After you jump through a few security hoops, you’ll be able to request your information as a zip file via the “request archive” button.
The archived information should include your account information, account history, apps and devices, account activity, interests and Ads data.
Once you’ve made the request, you’ll need to wait — and should receive an in-app notification when the archive is ready to be downloaded. You’ve have a limited amount of time to access the files.
How else can I prepare in case Twitter shuts down?
Given that Twitter has been widely used for public communication, some political figures and bodies are making preparations in case it shuts down.
For example, Rep. Alexandria Ocasio-Cortez (D-N.Y.) shared her Instagram handle and email with her 13.5 million Twitter followers, and a number of state agencies in the United States have announced alternative ways of keeping informed. Seattle’s Office of Emergency Management has told residents how to sign up for emergency alerts by text message, phone or email in case Twitter shuts down. A number of journalists have also started tweeting out their email or other contact details.
Tweet your own alternative online locations and pin that Tweet to your twitter feed. If you have people with whom you communicate only via Twitter DM, reach out and ask for alternative contact details. If you decide to post your contact information on Twitter, take care to share only details you are comfortable being made public.
Avoid deleting your Twitter account completely for now. That will prevent your old user name from being made available to someone else, so it cannot be used for scams or impersonation.
What alternatives to Twitter are there?
There is no exact replica for Twitter, and there hasn’t been enough time since Musk took over for a real replacement to emerge. Popular creators are sharing links to their Patreon accounts, newsletters and Instagrams. People could spend more time on established options such as Reddit, LinkedIn, Tumblr or even Facebook groups. As far as a place to spent hours scrolling, TikTok is the most popular alternative.
One of the most talked about Twitter alternatives has been the German social network Mastodon, which describes itself as the largest decentralized social network on the internet.
Searches for Mastodon first spiked after Musk announced a Twitter takeover bid in April. More than 70,000 users joined Mastodon the day after he officially took over, according to the platform, with over 1 million accounts added by Nov. 12.
Mastodon is not the same as Twitter, however: The site has far fewer users, and instead of signing up to a central site, people join separate sites, or servers. Reviews have been mixed, with many finding it confusing and overly technical.