What happened:
Error message logged in Grafana t=2020-10-23T14:56:24+0000 lvl=eror msg="Failed to get render key from cache" logger=rendering renderer=http error="cache item not found"

What you expected to happen:
No error message.

How to reproduce it (as minimally and precisely as possible):
Render a panel and refresh the request in browser multiple times frequently.

Anything else we need to know?:
After investigation it has been concluded that browser rendering is not cancelled server side when client (Grafana) cancel a request.

Environment:

• Grafana Image Renderer version: master / 2.0.0
• Grafana version: master
• Installed plugin or remote renderer service: Both