Uncaught Error: Call to undefined function json_decode()

[Anim3x]

Could you please help to resolve installation error.
I'm running admin/install.php script and nginx writes error .
The problem is in incorrect path to fancybox files. It parsed double /admin/admin to fancybox dirs.

PHP Code:

2018/12/01 22:44:35 [error] 3102#0: *353 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function json_decode() in /web/project.local/admin/inc/template_functions.php:1029
Stack trace:
#0 /web/project.local/admin/template/header.php(63): get_api_details()
#1 /web/project.local/admin/inc/template_functions.php(24): include('/web/project.lo...')
#2 /web/project.local/admin/install.php(129): get_template('header', 'GetSimple &raqu...')
#3 {main}
  thrown in /web/project.local/admin/inc/template_functions.php on line 1029" while reading response header from upstream, client: 127.0.0.1, server: project.local, request: "GET /admin/install.php HTTP/1.1", upstream: "fastcgi://unix:/run/php-fpm/www.sock:", host: "project.local"
2018/12/01 22:44:35 [error] 3102#0: *354 open() "/web/project.local/admin/admin/template/js/fancybox/jquery.fancybox.css" failed (2: No such file or directory), client: 127.0.0.1, server: project.local, request: "GET /admin/admin/template/js/fancybox/jquery.fancybox.css?v=2.0.4 HTTP/1.1", host: "project.local", referrer: "http://project.local/admin/install.php"
2018/12/01 22:44:35 [error] 3102#0: *354 open() "/web/project.local/admin/admin/template/js/fancybox/jquery.fancybox.pack.js" failed (2: No such file or directory), client: 127.0.0.1, server: project.local, request: "GET /admin/admin/template/js/fancybox/jquery.fancybox.pack.js?v=2.0.4 HTTP/1.1", host: "project.local", referrer: "http://project.local/admin/install.php"
2018/12/01 22:44:35 [error] 3102#0: *353 open() "/web/project.local/admin/admin/template/js/fancybox/jquery.fancybox.pack.js" failed (2: No such file or directory), client: 127.0.0.1, server: project.local, request: "GET /admin/admin/template/js/fancybox/jquery.fancybox.pack.js?v=2.0.4 HTTP/1.1", host: "project.local", referrer: "http://project.local/admin/install.php" 


Thank you in advance.