Magento Error 503 Backend fetch failed

Question

we have an AWS hosting, suddenly we got this below issue.

Error 503 Backend fetch failed Backend fetch failed

Guru Meditation: XID: 65561

Varnish cache server

we cant understand what's causing this issue. it is from AWS hosting or from project config.

please help with this.

Answer 1

As the error message states Varnish cannot communicate with the content (Magento2) server.

If you are using health checks in your Varnish VCL, varnish will also show this error if the content server is "unhealthy".

To check your content server status login to the varnish server and enter varnish admin with the varnishadm command.

Enter backend.list

varnish> backend.list
200
Backend name                                         Admin  Probe  Health   Last change
magento2_php_apache_1                                probe  10/10  healthy  Mon, 22 Feb 2021

If you are not using the health probe check network communications between varnish and the magento 2 server (if they are seperate servers.)

Answer 2

Please have a look at https://magento.stackexchange.com/a/316381/86404 for a more detailed answer. It uses the varnishlog binary to get more insight in why an HTTP/503 is returned.

Answer 3

Thanks, guys but I resolved this issue there was nginx.config.sample file was missing from project directory, so replaced it and restarted the server. it resolved this issue. but really thanks for your support.