Error 500 in frontend on dev server

When accessing the frontend on the development server today, I see an error:

500
Service Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problem

This happens when the frontend is unable to communicate with the backend. I've checked that the backend is running.

In the past there have been errors where host machine can't resolve its own hostname, or the machine can't communicate with itself using the external hostname. Dave and Soumik have been involved in fixing similar problems.

added To Do label

Dave corrected this error; it was a DNS problem.

closed