we are using Magento 2.3.5 with following setup:
User >> NGINX >> VARNISH (locale Docker) >> APACHE + PHP
Randomly some Requests returned by Nginx with 502. log file says:
recv() failed (104: Connection reset by peer) while reading response header from upstream
or
upstream prematurely closed connection while reading response header from upstream
The error comes from varnish:
Child (23669) Panic message: Assert error in VEP_Init(), cache/cache_esi_parse.c line 1039: Condition((vep) != 0) not true. thread = (cache-worker) version = varnish-4.0.5 revision 07eff4c29 ident = Linux,3.10.0-1160.21.1.el7.x86_64,x86_64,-smalloc,-smalloc,-hcritbit,epoll Backtrace: 0x55ed00ab6dc3: varnishd(+0x3edc3) [0x55ed00ab6dc3] 0x55ed00a9d16f: varnishd(VEP_Init+0x29f) [0x55ed00a9d16f] 0x55ed00a9a59a: varnishd(vfp_esi_gzip_pull+0x1ea) [0x55ed00a9a59a] 0x55ed00aa3a3e: varnishd(VFP_Fetch_Body+0x6e) [0x55ed00aa3a3e] 0x55ed00aa0839: varnishd(+0x28839) [0x55ed00aa0839] 0x55ed00aba07d: varnishd(Pool_Work_Thread+0x39d) [0x55ed00aba07d] 0x55ed00acf372: varnishd(+0x57372) [0x55ed00acf372] 0x7fd536c9ae25: /lib64/libpthread.so.0(+0x7e25) [0x7fd536c9ae25] 0x7fd5369c834d: /lib64/libc.so.6(clone+0x6d) [0x7fd5369c834d] busyobj = 0x7fd524d00020 { ws = 0x7fd524d000e0 { OVERFLOW id = ""o", {s,f,r,e} = {0x7fd524d02008,+90136,(nil),+90136}, },
The problem is: There is no way to reproduce this failure. It seems like it happens randomly. I know Varnish Version 4 is not the latest, but worked like a charme for month in our setup.
Is there anybody out there with a additional idea, where to search for the solution? Thanks in advanced