Error: cannot open display: :99

We are testing out circleci. Until this afternoon (CET) all was shiny and planned to add containers.

However: without changing the image much, all tests fail now.
26 07 2017 13:07:27.070:ERROR [launcher]: Firefox stdout:
26 07 2017 13:07:27.070:ERROR [launcher]: Firefox stderr: Unable to init server: Could not connect: Connection refused
Error: cannot open display: :99

I changed the image to own based on circleci, but no change. It is based on circleci/php:7.0-cli-node-browsers

Karma is the test runner that tries to open firefox.

See also Default Xvfb stopped working It is resolved now.