Angular development moves so quickly that there's a really good chance you'll have to troubleshoot your installation. Below are a few common problems I run into all the time.

ng build errors

I received this somewhat cryptic message while trying to run ng build.

You have to be inside an angular-cli project in order to use the build command after reinstall of angular-cli

After spending some time digging through StackOverflow I finally figured out how to just re-do the installation.

Conservative Fix

The conservative approach is to simply uninstall and re-install Angular cli.

Globally remove Angular client.

npm uninstall -g angular-cli @angular/cli

Locally remove your Angular client.

npm uninstall --save angular-cli

Globally re-install the Angular client.

npm install -g @angular/cli@latest

Aggressive Fix

If the conservative approach doesn't work, then this should work 90% of the time. After you uninstall Angular, do a force NPM clean both globally and locally.

Tell Node Package Manager to clean it's cache at the global level.

npm -g cache clean --force

Tell Node Package Manager to clean it's cache at the local level.

npm cache clean --force

Port Already in Use

Port 4200 is already in use. Use '--port' to specify a different port.

If you see this error, run the command below:

sudo lsof -t -i tcp:4200 | xargs kill -9  

This command will list out any processes that are using port 4200 and force quit them (aka -9).