On Mon, 25 Nov 2019 20:33:09 GMT, Erdem wrote:

I tried to kill application from the command line.

$ kill 2688
$ sudo kill 2688

I should be able to kill application using this command.

$ sudo kill -9 {PID}

The real problem was that I was using Ctrl-Z instead of Ctrl-C to terminate a vibe.d application.