Varnish returning synthetic 500 error even though it has stale content it should serve. But only seems to happen during/after a burst of traffic

Hi, One of our websites usually has quite a low but steady stream of visitors, but occationally we get a sudden surge of requests over a very short time period (about 1-2 minutes). Varnish seems to handle the load fine, but the backends struggle with this. But I have noticed that Varnish

Re: Varnish returning synthetic 500 error even though it has stale content it should serve. But only seems to happen during/after a burst of traffic

Could be a vary issue, can you post the output of `varnishlog -d -g request -q 'RespStaus eq 500'? Please anonymize the bits you don't want us to see by replacing them with "XX", but don't simply remove them. In the meantime, here's a cheat sheet to get started with varnishlog:

Re: Varnish returning synthetic 500 error even though it has stale content it should serve. But only seems to happen during/after a burst of traffic

> Could be a vary issue Ah, I remember hearing about that earlier, and made a mental note to read up on that. But I forgot all about it. Now I did just that, and boy was that a cold shower for me! I definitely need to unset that header. But why, for the love of all that is holy, does Varnish

Re: Varnish returning synthetic 500 error even though it has stale content it should serve. But only seems to happen during/after a burst of traffic

> Ah, I remember hearing about that earlier, and made a mental note to read up on that. But I forgot all about it. Now I did just that, and boy was that a cold shower for me! I definitely need to unset that header. But why, for the love of all that is holy, does Varnish not include the vary-data