Social media giant Twitter is back up after an outage left users unable to log on for nearly two hours. The company said that a change to an “internal configuration” caused the problem, but it has since been fixed. The firm did not say how widespread the problem was, but the issue seemed to affect both web and app versions of the platform. The site Downdetector.com showed around 70,000 reports at the peak of the outage, but by 8.45pm reports were down to just a couple of hundred. A live outage map showed problems centred in the US, east Asia and western Europe. Shares fell for the company on the New York Stock Exchange during the outage. The downtime came as Donald Trump was hosted a social media conference at the White House alongside like-minded critics of big tech.