Cannot find module './in-memory-data-service' in tour of heroes for Angular2

Question

I am trying to work through the Angular2 tour of heroes app, and am running into bugs on the Http section of the tutorial.

At first I was getting the error:

Answer 1

I got this error in 2020. I was running the server and running ng commands in another terminal.

Restarting the server did the trick. (CTRL+C, ng serve)