I'm getting error 500 in my backend of the sandbox
Error:
2018/08/21 17:52:17 [error] 9730#9730: *6023744 FastCGI sent in stderr: "PHP message: PHP Fatal error: Call to undefined function random_bytes() in /home/sandbox/domains/sandbox.com/public_html/classes/Rijndael.php on line 77" while reading response header from upstream, client: xx.xxx.xxx.xxx, server: sandbox.com, request: "GET /adminXXXXXXX/ HTTP/2.0", upstream: "fastcgi://127.0.0.1:8012", host: "sandbox.com"
Some section of the frontend doesn't work too, like categories page.
Products pages are working but in the logs the error is there for them too.
I already restarted php-fpm and nginx