View the original community article here
Last tested: Mar 18, 2020
This error will happen if Looker loses communication with Chromium while it's rendering a PNG. The most common cause of this is Chromium not having enough resources to run, and can be especially bad in containerized deployments of Looker that don't have enough memory or shared memory -- specifically not enough allocated to /dev/shm.
The error message will look slightly different if a PDF is being rendered:
session.command.page.cap…gQuality, viewPort, true) must not be null