The part about varnish reminded me of a story... So Europe is trying to get rid of lead found in solder that is found on almost all circuit boards. However, removing lead leaves a mixture where the tin will, over time, generate 'whiskers' that grow off the surface. They tried to increase the thickness and strength of the varnish (conformal coating). Sometimes it worked, but sometimes the whiskers still managed to punch through. In some instances, the whiskers can grow long enough to contact other circuit elements and cause a malfunction.
This error appears when custom health checks report a backend as down. It typically occurs when a Fastly edge server receives a client request and must make a request to your origin, but because the backend is considered unhealthy, Fastly doesn't try to send the request at all.
Reboot your Wi-Fi router. Then try the enema.
Guru Mediation, on the other hand, sounds like something you'd find at an ashram.
@p-nullifidian Fastly is the platform they were using. It's buggy.
@barjoe Hard to believe this of such a prominent radio station as KCBS, San Francisco!