How to fix error 503 backend fetch failed varnish cache server

This is the solution guide regarding how to fix error 503 backend fetch failed varnish cache server.  If your website is using varnish cache, then we will help you so you can resolve this issue for free. So, are you ready? If that’s the YES, the dive in and look for how you can fix it!

We already discussed about what are the common reasons of Error 503 backend Fetch Failed and also shared 7 working quick fixes solutions. If you haven’t checked that then I would highly encourage you to go and checkout that guide once. To know more about how to fix varnish cache – checkout below.

What is error 503 backend fetch failed varnish cache server

If you are visiting a website that caches its content using Varnish Cache or if you have Varnish Cache installed on your own website, there is a good probability that at some point you will come across the following Varnish Cache server error: XID number associated with an Error 503 Service Unavailable message.

The web server that was trying to be contacted returned an error 503 backend fetch failed varnish cache server, which indicates that it is now unavailable. This could be because the server is overloaded, is currently undergoing maintenance, or is not completely functional for another reason.

how to fix error 503 backend fetch failed varnish cache server

Why you are getting an Error on a Varnish Cache Server

When you see this error in relation to Varnish Cache, it means that the website you are visiting is using Varnish Cache to cache and serve content, but that Varnish Cache is unable to reach the back end server.

This error can only occur when the website you are visiting uses Varnish Cache to cache and serve content. The Guru Meditation error is generated by Varnish Cache when a connection has been idle for an extended period of time or when the Varnish Cache server has sent an excessive number of requests to a back end server without receiving a response.

Varnish Cache will display the 503 error message rather than making an infinite number of requests to a back end that is unhealthy. This is done to inform the visitor (and the owner of the website) that it is likely the website manager is already working on a fix and that your best bet is to try again at a later time. If you are the manager or owner of this website and are unsure of why you are getting this response, read on to find out more information about it.

How to fix error 503 backend fetch failed varnish cache server

So, how do you go about fixing the problem if your website is generating a Guru Meditation 503 error using Varnish Cache? Utilizing varnishlog, you should first examine the logs to find all of the 503 problems that have occurred. It is possible to get varnishlog to log 503 problems by using the command that is provided below from within Varnish Cache:

$ varnishlog -q ‘RespStatus == 503’ -g request

Because your back end is either offline or sick, you will consistently receive 503 errors in your logs. In this particular scenario, varnishlog might generate an error message that reads “FetchError c no backend connection.”

Whether the port that Varnish Cache is trying to connect to, the origin server, and your HTTP service, such as Apache or Nginx, are all functioning correctly, then you should check to see if your back end needs any troubleshooting. If it does, then you can move on to the next step in this process.

If your back end does appear to be operational, but you are still receiving an error code 503 from Varnish Cache, there is likely an issue with the connection that your web server has established to Varnish Cache or with the settings of Varnish Cache.

If your back end is responding but Varnish Cache is returning 503, we frequently find that the cause is timeouts on our end. In the backend default VCL section, you can edit or add a.connect timeout = Xs and a.first byte timeout = Xs to a timeout length that is suitable for your web server.

More information regarding the various timeouts that may take place in Varnish Cache may be found in the Varnish Cache Software. Another useful piece of advice is to turn off the KeepAlive feature, which will cause idle connections to be severed. The following is what this would look like:

“origin”: {
“address”: “”,
“disable_keepalive”: true

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