Getting same error at every website including webmail. excluding control panel. Please give some solution ASAP.
this issue is by v1.8.10 update?
We only reduced the keepalive_limit in Nginx not so that can’t be the issue …
How can i resolve the issue?
please give solution, all sites are down.
Check error logs …
got unique resolution 
I have suspended and unsuspected all user one by one. it works
after some time, still getting error
400 Bad Request
Request Header Or Cookie Too Large
error after update only.
We haven’t changed anything regarding it …
Yes, but i am asking for help. Please help me.
Anyone please help! Important sites are down.
I just can repeat what @eris already wrote: Check and provide your logs, we can’t and will not guess “what’s wrong”.
I dont gonna debug from a printscreen, also you need to check for error log, not access.
Sorry, type mistake it’s error log only
I have copy all files from /usr/local/hestia/data/templates/web/nginx/php-fpm/ to /usr/local/hestia/data/templates/web/nginx/.
restarted the nginx
after i suspended user and unsuspended after some time.
So, all website under the user is working fine.
BUT, WEBMAIL NOT WOKRING.
webmail giving same error
idk, copying files from php-fpm to nginx is good or not.
at the end issue is the same
400 Bad Request
Request Header Or Cookie Too Large
nginx
Templates from /usr/local/hestia/data/templates/web/nginx/php-fpm/ should never work under:
/usr/local/hestia/data/templates/web/nginx/
Unless you have messed a lot of thing up in the past
Did you switch over from Nginx + Apache2 to Nginx only in the past?
Yes, i switched to nginx only from nginx + apache