WP Toolkit sw-cp-server fails to start: "could not open error log file"

Symptoms

The sw-cp-server service fails to start and the following is reported when checking the status of the service:

nginx: [alert] could not open error log file: open() "/var/log/sw-cp-server/error_log" failed (2: No such file or directory)
sw-cp-serverd[14792]: 2021/04/22 00:12:20 [emerg] 14792#0: open() "/var/log/sw-cp-server/error_log" failed (2: No such file or directory)
sw-cp-serverd[14792]: nginx: configuration file /etc/sw-cp-server/config test failed
sw-cp-server.service: control process exited, code=exited status=1
Failed to start Startup script for Plesk control panel server.
Unit sw-cp-server.service entered failed state.
sw-cp-server.service failed.

Run the following command in SSH or WHM » Terminal as root to check the status of sw-cp-server:

systemctl status sw-cp-server

Description 

The sw-cp-server service is failing to start because the error log file does not exist.

Workaround

If the error log or log directory do not exist, recreate them by running the following commands in SSH or WHM » Terminal as Root:

mkdir /var/log/sw-cp-server/

touch /var/log/sw-cp-server/error_log

Once complete, run the following command to start the sw-cp-server service:

systemctl start sw-cp-server