nginx error after rebooting

I've installed redmine and it had been working correctly till rebooting the host. Now I get below error in the logs:

connect() to unix:/srv/redmine/run/unicorn.sock failed (111: Connection refused) while connecting to upstream, client: x.x.x.x, server: , request: "GET / HTTP/1.1", upstream: "http://unix:/srv/redmine/run/unicorn.sock:/", host: "x.x.x.x"

I've used this link to install redmine on debian 8 with unicorn. nginx,...