Magento 2.3 Varnish 503 Backend fetch failed

Question

varnish server gives back error message:

Error 503 Backend fetch failed
Backend fetch failed
Guru Meditation:
XID: 131307

varnish log info:

Varnish cache server 
# varnishlog -q 'RespStatus == 503'
* << Request >> 131307
- Begin req 196933 rxreq
- Timestamp Start: 1577129611.804607 0.000000 0.000000
- Timestamp Req: 1577129611.804607 0.000000 0.000000
- ReqStart 172.19.0.1 57376
- ReqMethod GET
- ReqURL /index.php/admin/customer/index/index/key/a1cb5649e0727c563c92b6873c654c996b94a4729dfdb8247ef3b57350c20ff2/
- ReqProtocol HTTP/1.1
- ReqHeader Host: m2.docker
- ReqHeader Connection: keep-alive
- ReqHeader Upgrade-Insecure-Requests: 1
- ReqHeader User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.88 Safari/537.36
- ReqHeader Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
- ReqHeader Referer: http://m2.docker/index.php/admin/admin/system_store/index/key/3685fd86510c4b9c1f7796f25f1b7fda21adcab527d13b0c3822bcb2d207ae40/
- ReqHeader Accept-Encoding: gzip, deflate
- ReqHeader Accept-Language: en-US,en;q=0.9,zh-CN;q=0.8,zh;q=0.7
- ReqHeader Cookie: admin=3c2d07d3c163dd84faed04865f7e1401; form_key=CgVTpyUNua3s7Ynq; private_content_version=e105233d30e3e7553aa81958343c8dfb; AMCVS_8F99160E571FC0427F000101%40AdobeOrg=1; s_cc=true; mage-translation-storage=%7B%7D; mage-translation-file-version=%7
- ReqHeader X-Forwarded-For: 172.19.0.1
- VCL_call RECV
- ReqURL /index.php/admin/customer/index/index/key/a1cb5649e0727c563c92b6873c654c996b94a4729dfdb8247ef3b57350c20ff2/
- ReqUnset Accept-Encoding: gzip, deflate
- ReqHeader Accept-Encoding: gzip
- ReqURL /index.php/admin/customer/index/index/key/a1cb5649e0727c563c92b6873c654c996b94a4729dfdb8247ef3b57350c20ff2/
- ReqURL /index.php/admin/customer/index/index/key/a1cb5649e0727c563c92b6873c654c996b94a4729dfdb8247ef3b57350c20ff2/
- ReqURL /index.php/admin/customer/index/index/key/a1cb5649e0727c563c92b6873c654c996b94a4729dfdb8247ef3b57350c20ff2/
- VCL_return hash
- VCL_call HASH
- VCL_return lookup
- Debug "XXXX MISS"
- VCL_call MISS
- VCL_return fetch
- Link bereq 196935 fetch
- Timestamp Fetch: 1577129676.180708 64.376101 64.376101
- RespProtocol HTTP/1.1
- RespStatus 503
- RespReason Backend fetch failed
- RespHeader Date: 2019年12月23日 19:34:36 GMT
- RespHeader Server: Varnish
- RespHeader Content-Type: text/html; charset=utf-8
- RespHeader Retry-After: 5
- RespHeader X-Varnish: 196934
- RespHeader Age: 0
- RespHeader Via: 1.1 varnish-v4
- VCL_call DELIVER
- RespUnset Age: 0
- RespUnset Server: Varnish
- RespUnset X-Varnish: 196934
- RespUnset Via: 1.1 varnish-v4
- VCL_return deliver
- Timestamp Process: 1577129676.180742 64.376135 0.000034
- RespHeader Content-Length: 283
- Debug "RES_MODE 2"
- RespHeader Connection: keep-alive
- Timestamp Resp: 1577129676.180834 64.376226 0.000092
- Debug "XXX REF 1"
- ReqAcct 1658 0 1658 175 283 458
- End

I have used the 'default.vcl' from Magento 2 backend export.

• Savvas Radevic: Have you tried restarting php-fpm, nginx/apache, varnish, in that order? Can you also post your httpd or nginx configuration regarding the varnish?
• Jeff Yu: Hi Savcas, thank you so much for your reply. I'm using docker image to make the Magento 2 dev environment. The web server is apache not Niginx.
• General Grievance: Does this answer your question? Magento 2 503 Backend Fetch Failed

Answer 1

for me this issue got resolved when i disabled magento csp module in local

php bin/magento module:disable Magento_Csp
php bin/magento c:f