how to fix unknown directive error in nginx?

I’m currently getting the following error with nginx:

$ sudo nginx -t
nginx: [emerg] unknown directive "sd#" in /etc/nginx/sites-enabled/default.save:27
nginx: configuration file /etc/nginx/nginx.conf test failed

As a result none of my reverse proxies work anymore. Anyone an idea what’s causing this and how I can fix it?

For the record: I made a small change in the config (copy pasted code some code in), but reverted back again after I got the error. At the time my reverse proxies where still functioning, but after a server reboot they all stopped functioning (which makes sense). Any help would be great, thanks!