Same issue here. Not sure what's going on, but here's the error log in /var/log/sw-cp-server/
2017/04/25 11:20:07 [error] 10193#0: *989 empty URI in redirect to named location "@err" while reading client request line, client: REMOVED, server: , request: "
and from the sw-engine log:
[25-Apr-2017 18:03:28] NOTICE: Terminating ...
[25-Apr-2017 18:03:28] NOTICE: exiting, bye-bye!
[25-Apr-2017 18:03:28] NOTICE: fpm is running, pid 14301
[25-Apr-2017 18:03:28] NOTICE: ready to handle connections
[25-Apr-2017 18:03:28] NOTICE: systemd monitor interval set to 10000ms
[25-Apr-2017 18:04:26] NOTICE: Terminating ...
[25-Apr-2017 18:04:26] NOTICE: exiting, bye-bye!
[25-Apr-2017 18:04:26] NOTICE: fpm is running, pid 23740
[25-Apr-2017 18:04:26] NOTICE: ready to handle connections
[25-Apr-2017 18:04:26] NOTICE: systemd monitor interval set to 10000ms
[25-Apr-2017 18:18:38] NOTICE: Terminating ...
[25-Apr-2017 18:18:38] NOTICE: exiting, bye-bye!
[25-Apr-2017 16:18:38] NOTICE: fpm is running, pid 503
[25-Apr-2017 16:18:38] NOTICE: ready to handle connections
[25-Apr-2017 16:18:38] NOTICE: systemd monitor interval set to 10000ms
[25-Apr-2017 16:26:26] NOTICE: Terminating ...
[25-Apr-2017 16:26:26] NOTICE: exiting, bye-bye!
[25-Apr-2017 16:26:26] NOTICE: fpm is running, pid 7198
[25-Apr-2017 16:26:26] NOTICE: ready to handle connections
[25-Apr-2017 16:26:26] NOTICE: systemd monitor interval set to 10000ms
[25-Apr-2017 16:59:15] NOTICE: Terminating ...
[25-Apr-2017 16:59:15] NOTICE: exiting, bye-bye!
[25-Apr-2017 16:59:15] NOTICE: fpm is running, pid 22668
[25-Apr-2017 16:59:15] NOTICE: ready to handle connections
[25-Apr-2017 16:59:15] NOTICE: systemd monitor interval set to 10000ms