Thousands of TikTok users in the UK, Europe and Australia have reported problems connecting to the social media site.
More than 3,000 users reported issues at lunchtime on Monday, according to Down Detector.
Users in London, Amsterdam, Paris, Milan, Madrid, and Naples reported outages.
There were also problems reported in Turkey, Greece, United Arab Emirates, Malaysia, and Indonesia.
Hundreds also reported issues with the app in Sydney, Melbourne and Perth.
Some 59 per cent of users reported problems with viewing videos, 35 per cent had issues logging into the app, and 5 per cent struggled to upload content.
By 2pm, many users said the app had started to work again.
A spokeswoman for TikTok told the Standard: "Earlier today we experienced a temporary issue in our Singapore data centre that caused short-term effects for users around usernames, profile photos, like counts, and follower lists.
"The issue has been resolved and service for our users is now fully restored.
"We are still investigating the root cause and apologise for the interruption our users experienced."
