My site is currently using --wpfc and I want to try --wpredis so I tried updating my cache by using this command:
ee site update www.example.com --wpredis
Type "y" to continue [n]: y
Adding repository for Redis, please wait...
Updating apt-cache, please wait...
Installing packages, please wait...
Running pre-update checks, please wait...
NGINX configuration check failed.
root@server:~# nginx -t
nginx: [emerg] unknown "srcache_fetch_status" variable
nginx: configuration file /etc/nginx/nginx.conf test failed