503后端提取失败-Varnish缓存服务器Laravel

Question

I have a Laravel web app and randomly in the admin I get the following error:

Error 503 backend fetch failed 
Guru Meditation:
XID: 499820
varnish cache server

I get this error even on the default Laravel login auth when I click login sometimes randomly it could throw this 503 error if I press back the session has started and I'm logged in.

I've had a look online but I'm not sure where to start to find out how to resolve this issue. many of the existing question on Stack seem to relate specifically to Magento CMS.

Answer 1

The backend fetch failed error is a very generic one.

You might have to dive deep into log files, as it can be caused by things like fatal PHP errors, nginx misconfiguration, exceeded timeouts and much more. Varnish simply "obfuscates" those and doesn't make it clear on what's going on behind it.

Your first step before checking log files might be using varnishlog to find out cause of backend fetch failed , eg:

varnishlog -d -q "BerespStatus == 503"