From November 20, 2020, rate limits anonymous and free authenticated use of Docker Hub went into effect, which makes the travis-ci fails, see details https://www.docker.com/increase-rate-limits
and the error is
toomanyrequests: You have reached your pull rate limit. You may increase the limit by authenticating and upgrading: https://www.docker.com/increase-rate-limit
The command "sudo docker pull ubuntu:focal" failed and exited with 1 during .
From November 20, 2020, rate limits anonymous and free authenticated use of Docker Hub went into effect, which makes the travis-ci fails, see details https://www.docker.com/increase-rate-limits
and the error is