Random HTTP 401 errors (File not found)

lately i setup my Haproxy server and now randomly 401 Error (File not found) errors occure. And when restarting Haproxy it works for around 10 minutes and than it again happens. Than you can spam F5 and every 3. Page just shows “File not found.”

OS: Archlinux

I will just send the config in here, maybe something is wrong with it:

    maxconn     20000
    #log         /var/log/ local0
    log /dev/log local0 info
    user        haproxy
    chroot      /usr/share/haproxy
    pidfile     /run/haproxy.pid

    log global
    mode    http
    option  httplog
    option  dontlognull
    timeout connect 5s
    timeout client  50s
    timeout server  50s

userlist auth-list
  group is-admin
  user [REMOVED] password [REMOVED] groups is-admin

frontend site
    bind        :80
    mode        http
    log         global
    stats       enable
    stats       uri     /haproxy?stats
    stats       realm   Strictly\ Private
    stats       auth    [REMOVED]
    option              httplog
    option              dontlognull
    option      http-keep-alive
    option      http_proxy
    option      forwardfor
    timeout     client  300s
    acl url_static  path_end    -i  .woff .ico .swf .svg .ttf .jpg .gif .png .css .js
    use_backend     site_cdns   if url_static
    use_backend     site_phpservers
    default_backend     site_phpservers
    errorfile       503     /etc/haproxy/errors/503.http
    errorfile           401     /etc/haproxy/errors/401.http

backend site_cdns
    mode    http
    balance roundrobin
    timeout connect 300s
    timeout server  300s
    timeout     queue   300s
    option      redispatch
    cookie CPG insert
    server [REMOVED] cookie SB check

backend site_phpservers
    mode    http
    balance     roundrobin 
    timeout     connect 5s
    timeout     server  30s
    timeout     queue   30s
    option      redispatch
    cookie CPG insert
    use-fcgi-app site_fpmsettings    
    server [REMOVED] cookie SA proto fcgi check

fcgi-app site_fpmsettings
    log-stderr global
    docroot /site
    index index.php
    path-info ^(/.+\.php)(/.*)?$

Appreciate any help!