Transport for London (TfL) has blamed a bug for making travel apps say all Tube lines were closed.
TfL was hit with queries on social media by confused commuters reacting to the bogus news about the line closures.
The travel body referred people to its website for more accurate information about the status of Tube lines.
Later, it said the "issue" had been reported to its web developers who had fixed the problem.
The problem with the apps emerged around 08:00 GMT - towards the end of the early rush hour in London. It meant that anyone looking to see if there would be any delays on their journey was told that no services were running.
The way that TfL shares its service information meant that several different apps that use the feed from the travel body were also reporting a network-wide shutdown.
Many people took to Twitter to ask what was happening on the tube to bring about such a massive service shut down.
Initially, TfL said there was no problem with its data feed. However, soon after it started responding to queries saying it had been notified of an "issue" which was being looked into by its web team.
To get more accurate information it told many on social media to refer to its webpages for "accurate" information.
The app was fixed and showing correct information by about 10:00 GMT.