If you develop Sharepoint Framework web parts (SPFx web parts) you probably familiar with one part of it’s development process – local web server which is launched with gulp:
gulp serve –nobrowser
It launches local web server on localhost:port which allows you to test SPFx web part on own dev environment (not release version) which consumes js and css files directly from this localhost:port address. So you may modify them and reload the page without redeploying app package to App catalog (which is time consuming if you develop js/css).
However sometimes local web server hangs without visible reasons. In order to avoid it you may stop it (Ctrl-C) and run again – but it also takes time and not always help. If you faced with this problem go to cmd window with launched gulp serve and try click Esc several times. If after that it will start to show output like this:
it will mean that server unfreezes and should work again now.