https://www.theguardian.com/world/2020/sep/24/users-report-issues-as-covid-19-app-launches-in-england-and-wales

Problems on Android and iPhone leave some unable to use the software at all

The launch of the NHS Covid-19 app in England and Wales has exposed problems with the programme, some of which were known about in advance, and some of which will come as a surprise to both the government and users.