A security mix-up has led to thousands of Twitter users needlessly changing their passwords.
The social network sent an email on Thursday asking users to change their passwords after a suspected security breach.
It also forcibly reset many other passwords to prevent access to affected accounts.
It seems that many users were indeed hacked, and that their private information had been accessed.
But officials later said they had over-estimated the scale of the attack, and many of the users sent emails were not affected after all.
Figures about how many users were affected have not been released, but many high profile accounts including comedian David Mitchell and the official Radio 4 Today Programme account apparently received emailed warnings.
Twitter said in a statement:
"We're committed to keeping Twitter a safe and open community. As part of that commitment, in instances when we believe an account may have been compromised, we reset the password and send an email letting the account owner know this has happened along with information about creating a new password.
"This is a routine part of our processes to protect our users.
"In this case, we unintentionally reset passwords of a larger number of accounts, beyond those that we believed to have been compromised. We apologize for any inconvenience or confusion this may have caused."