Windows 10 CMD: Ctrl + C not killing processes?

One possibility is that you have changed the CMD (cmd.exe) defaults. To restore the defaults, right-click on the CMD window's title bar and choose "Defaults".

Although Ctrl+C works fine on my PC in normal mode, perhaps you have UAC disabled and need to run CMD in administrator mode in order for Ctrl+C to work. To run in CMD in administrator mode, click on "Search", type in "cmd", right-click on "Command Prompt (Desktop app)", and choose "Run as administrator".

Just ran into this issue myself. It seems that when I return to cmd and left click in the black screen, the window title is prefixed with "Select" as though I am trying to highlight text. The first CTRL + C kills the select mode and the second CTRL + C kills the process. If I right click the window or left click the title bar as opposed to the window itself I do not get the "Select" event and CTRL + C works first time.

I believe you can also disable quick editing and this effectively stops you from highlights thus solving the issue if highlighting text in cmd is of no importance to you, the second alternative is just right click the window to reselect it.

I had the same problem on Windows 10. Ctrl+BREAK worked for me.