This is part of our Four Lines Modernisation work to upgrade the District, Circle, Metropolitan and Hammersmith & City lines.
Despite extensive testing of the new signalling outside of operating hours, we have had issues with software reliability on Metropolitan line trains when the live service is running. This is causing disruption and delays to some journeys.
We had tested the new signalling extensively using 500 trains, with good results. But when we run a full service in a live environment we experienced issues with the trains connecting to the system. This is the main cause of the faulty train message you have been seeing.
We have worked with our signalling supplier to identify how to address these issues and fixes are now being developed. Two software updates are scheduled to be completed by the end of January 2020 - we are confident these will improve the situation.
Fixes to this new and complex system need rigorous testing and safety approvals, which takes time. We fully understand how frustrating this is.
We are working 24-7 to tackle the delays and improve the service as soon as possible.
To address issues on the Metropolitan line, we are: