Error 503 Backend fetch failed on all website hosted in our server

Hi,

Recently all website Hosted in my server are showing below error, its seems the error are because of Varnish Cache Serve.

I have tried many way to resolve this issue but nothing worked, Wordpress website are showing below error

Error 503 Backend fetch failed
Backend fetch failed
Guru Meditation:
XID: 262174
Varnish cache server

Other PHP websites are showing below error
Error 503 Backend fetch failed

Can some help me to resolve this issue, it will be helpful..

Any one have any idea to resolve this issue, please help

You'll have to look at the varnish logs. Do you have a WP varnish plugin to expiry the cache?

Hi tried many way the varnish logs are not in the log folder I also run it from the log manager but the file was not generating in the Var/varnishn folder. Now each and every time I need to restart Apache Webserver and Varnish Cache Server to the website back to online If some one can help me that will be helpfull.

You'll have to look at the varnish logs. Do you have a WP varnish plugin to expiry the cache?

I would take the caching aspect out of the loop, unless you really think you need it. It's usually the last step in deployment before going live. And in all honesty, unless you have a lot of RAM available or fast disks, Varnish introduces a whole level of complexity and tends to be a common break point. I've only ever implemented it on one very high traffic server. But ultimately, I got even better results from using Cloudflare's infrastructure.

The best bang-for-your-buck combo on CWP is with Nginx (least troublesome to configure and manage, far better performance than Apache). Varnish is only if you absolutely need to milk every last bit of performance out of your existing server.