# Magento2 Varnish 503 Backend Fetch Failed Problem **SOLVED

URL: https://sohaib.com/blog/magento-503-backend-fetch-failed
Author: Sohaib Khan
Published: Jul 17, 2016
Updated: Sep 8, 2026
Category: E-commerce Solutions

> I've M2.10 , Varnish , Redis and Nginx intalled and using Php7.08 with installed after doing a lot of research I wasn't able to find a solution for this. I was moving around attributes from groups to un-assigned…

I've  M2.10 , Varnish , Redis and Nginx intalled and using Php7.08 with installed after doing a lot of research I wasn't able to find a solution for this. I was moving around attributes from groups to un-assigned group in Magento 2.10, I notice I was having issue with Varnish and the error was Varnish 503 Backend Fetch Failed. The problem was in "clean\_cache\_by\_tags" function in Magento. I think it's an error clearing the cache in php7 & magento2. Quick fix is to turn off block\_html cache. Everything works in Php 5.6x but in PHP7.08 its causing a lot of problem. Should I downgrade or stay upgraded is the question ? _**After installing php5.6 it appears everything seems to be working fine**_