Due to a change in Coinbase's ticker API, an update will need to be made on the server to continue using Coinbase Exchange (GDAX) as a price source.
Log into your server's command line (SSH on Mac/Linux, PuTTY on Windows), and run the following two commands individually:
cd /usr/local/lib/node_modules/lamassu-server/ npm install lamassu-coinbase@latest
Thereafter, restart the server process in order to restore service, run:
stop lamassu-server start lamassu-server LAMASSU_ENV=debug
For information on configuring Coinbase Exchange (GDAX) with your machine, see this article.