Instagram users are finding themselves unable to login to the app after an apparent error.
They are instead shown a message and told they are unable to get into the account.
"Oops, an error occurred," reads one of the messages.
Another is more confusing, and shows "error" in large text alongside the words "challenge_required".
There appears to be no obvious fix for the problem.
But it appears to only be affecting a limited number of users. Many people appear to be able to get on the app as normal, even after logging out.
Over summer, Instagram suffered a major outage that also took down Facebook and WhatsApp.
The latest issue appears to be relatively minor, affecting only a limited number of users and only when they attempt to login.
