Users in the U.S. who opened the app were greeted with a message that read, "Sorry, TikTok isn't available right now."

Challenges came in tandem with TikTok’s success. U.S. officials expressed concerns about the company’s roots and ownership, pointing to laws in China that require Chinese companies to hand over data requested by the government. Another concern became the proprietary algorithm that populates what users see on the app.

A law that prohibits mobile app stores and internet hosting services from distributing the video-sharing platform to U.S. users takes effect on Sunday.

A lawyer for TikTok content creators on Friday urged the White House and the Justice Department to clarify to Apple and Google that they can continue to offer the TikTok short-video app in app stores on Sunday when a legal ban is set to take effect.

The company announced the shutdown in a pop-up message on the app that only allows users to "learn more" about the federal law or close the app.

TikTok said it will be forced to go dark on January 19, the day the ban is set to take effect, without more assurances it won't be enforced.

TikTok says service providers need "clarity" to ensure the app remains available when the ban takes effect on Sunday.

Trump spoke to NBC News' Kristen Welker in an exclusive phone interview Saturday, discussing his plans on what to do about the popular social media app.

The White House on Saturday called TikTok’s statement warning that it will “go dark” on Sunday unless President Biden steps in a “stunt,” arguing the app doesn’t have to take action before President-elect Trump is sworn in.

The White House on Friday said that the TikTok ban will fall to President-elect Trump’s administration after the Supreme Court upheld a law requiring the app’s China-based parent

TikTok's app was removed from prominent app stores on Saturday evening just before a federal law that bans the popular social media platform went into effect.