Zabbix 4.0 + php7.1 Uncaught Exception

[naxim]

Hello, guys!
I try to deploy zabbix server 4.0 + nginx + php 7.1, but it seems I catched a bug.

I've installed postgresql, zabbix-server and wanted to install zabbix-frontend-php. But... when I've done all installation steps I got blank page in address "http://zabbix/setup.php". Logs were clear. Then I wanted to debug this situation and put simple test.php (<?php phpinfo(); ?>) with zabbix php files. And test.php worked! I got an information about php. I thought, ok, I have to debug php. And I added into setup.php this code:

ini_set('display_errors',1);
error_reporting(E_ALL); 

And finally, I saw the error. When I tried http://zabbix.naxim-home.ru/setup.php I get this:

"Fatal error: Uncaught Exception: Cannot start session. in /usr/share/zabbix/include/classes/core/CSession.php:50 Stack trace: #0 /usr/share/zabbix/setup.php(63): CSession::start() #1 {main} thrown in /usr/share/zabbix/include/classes/core/CSession.php on line 50"

Any ideas? Yes, I googled this error and tried to fix this by chown and chmod:

cat /etc/php/7.1/fpm/php-fpm.conf | grep save_path
php_value[session.save_path]    = /var/lib/php/session

/var/lib/php# ls -l
итого 8
drwxr-xr-x 3 nginx nginx 4096 май 21 14:42 modules
-rwxrwxrwx 1 nginx nginx    0 май 21 21:08 session
drwx-wx-wt 2 nginx nginx 4096 мар  3 12:50 sessions

The problem is still there... Anybody can help me??
PS I'm noob in nginx and php and most of configs were copy-pasted from intenet, but it's just test deploying.

Versions:
uname -a
Linux monitoring0-s 3.16.0-4-686-pae #1 SMP Debian 3.16.7-ckt11-1+deb8u3 (2015-08-04) i686 GNU/Linux

nginx -V
nginx version: nginx/1.15.12
built by gcc 4.9.2 (Debian 4.9.2-10+deb8u2)
built with OpenSSL 1.0.1t 3 May 2016 (running with OpenSSL 1.0.1k 8 Jan 2015)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-g -O2 -fPIE -fstack-protector-strong -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fPIC' --with-ld-opt='-fPIE -pie -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -pie'

php -v
PHP 7.1.29-1+0~20190503100939.18+jessie~1.gbp946c98 (cli) (built: May 4 2019 08:47:40) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies
with Zend OPcache v7.1.29-1+0~20190503100939.18+jessie~1.gbp946c98, Copyright (c) 1999-2018, by Zend Technologies

zabbix-frontend-php_4.0.7-1+jessie_all.deb
zabbix-server-pgsql_4.0.7-1+jessie_i386.deb