WASHINGTON — TikTok was not available for users in the U.S. on Saturday as a ban on the popular social media platform officially went into effect.

TikTok greeted users opening the app Saturday night with the message, “Sorry, TikTok isn’t available right now.”

“A law banning TikTok has been enacted in the U.S.,” the message continued. “Unfortunately, that means you can’t use TikTok for now. We are fortunate that President Trump has indicated that he will work with us on a solution to reinstate TikTok once he takes office. Please stay tuned!”

A spokesperson for the Trump transition team did not immediately respond to a request for comment Saturday night about the app’s notification praising the president-elect specifically.

The message then prompted users to close the app or learn more. On the website landing page, the message had an additional line informing users that they could still log in to download their data.

The app also appeared to be removed from Apple and Google’s app stores in the U.S., making it unavailable to download.

TikTok has 170 million U.S. users.

Other Bytedance apps including CapCut, Lemon8 and Gauth displayed similar messages and also became unavailable to many U.S. users Saturday evening.

The shut down of TikTok follows several tense days of uncertainty for the app leading up to Sunday, when a ban on TikTok is supposed to go into effect in the United States.

In April, President Joe Biden signed a law that mandated that TikTok’s Chinese-owned parent company ByteDance sell TikTok to a non-Chinese owner, or TikTok would be banned. The Supreme Court upheld the law on Friday, paving the way for the app to shut down in the United States.

But the Biden administration released a statement on Friday indicating that it would leave the law’s enforcement up to the Trump administration. Since the law was made, it became deeply unpopular with users and many Americans, and many TikTok users began fleeing to Chinese social media apps.

The Biden Administration’s comments that it would not enforce the ban when it’s set to take effect on Sunday created uncertainty about whether the app would be made unavailable or remain online for Americans.

Lawmakers on both sides of the aisle have decried TikTok as a threat to national security because it is owned by a Chinese company. TikTok critics argued that the Chinese government could use the app to access Americans’ data or influence the type of content Americans watched.

But the company has pushed back on lawmakers’ concerns, instead painting the looming ban as a free speech and censorship issue. TikTok CEO Shou Zi Chew has said that the app is safe and secure.

The app’s future is far from certain. Earlier on Saturday, President-elect Donald Trump told NBC News’ Kristen Welker that he will “most likely” give the app a 90-day extension of the Sunday deadline for ByteDance to sell the app or have TikTok banned in the U.S.

“The 90-day extension is something that will be most likely done, because it’s appropriate,” Trump said.

Trump has alternated on his stance on TikTok. In 2020 he said he wanted to ban the app. Years later, Trump reversed his position before making his own TikTok account during the 2024 presidential campaign. In one video, Trump said he would “save TikTok.”

In a video message posted on TikTok Friday, Chew thanked Trump, saying the incoming president strongly supported TikTok. Chew cited Trump’s popularity on the app, where he is the most followed American politician, with over 14 million followers.

Some TikTok users moved to rival social media platforms to commiserate over the app’s shutdown.

The popular Liza Minnelli Outlives X account weighed in, alerting followers that the actress outlived the app, “forcing many people to find new ways to waste time.”

One user compared TikTok to the Detroit Lions because they were both “eliminated by Washington.”

Members of Trump’s administration remain divided over the app, with some, like incoming Federal Communications Commission Chair Brendan Carr, advocating against Chinese influence over the app, while others, like unofficial government spending overseer Elon Musk, are pushing for TikTok to remain available on the basis of free speech.

On Friday, Trump posted on Truth Social: “The Supreme Court decision was expected, and everyone must respect it. My decision on TikTok will be made in the not-too-distant future, but I must have time to review the situation. Stay tuned!”

One way TikTok could comply with the law and stay active in the U.S. is if it negotiates a sale of the app to an American owner. Trump could maintain Biden’s decision not to enforce the law, but it’s unclear how long that would hold.

Users on TikTok have mourned the app’s potential downfall earlier this week, with many top creators making compilations of their most viral moments on the app or asking their followers to follow them on other platforms. Many TikTok users have flooded a Chinese app called RedNote in protest of the government, but it poses an even greater security threat than TikTok, according to experts who spoke with NBC News.