Error thrown when using the Gatsby CLI after install - "Error: Cannot find module 'detect-port'"

Description

When I installed the gatsby CLI, I was unable to run it; it throws this exception in the command line:

This is only resolveable by globally installing detect-port, at which point everything is fine. Perhaps a missing dependency that wasn’t included?

Steps to reproduce

1. Install gatsby-cli globally.
2. Try to create a new site with the Gatsby CLI per the tutorial (or run gatsby -v - any command will cause the failure it seems)
3. The above error is spat out

Expected result

What should happen?

It should not throw

Actual result

It throws an exception saying that detect-port could not be found.

Environment

System: OS: macOS 10.15.4 CPU: (16) x64 Intel® Core™ i9-9880H CPU @ 2.30GHz Shell: 5.7.1 - /bin/zsh Binaries: Node: 12.13.0 - ~/.nvm/versions/node/v12.13.0/bin/node Yarn: 1.22.4 - /usr/local/bin/yarn npm: 6.14.4 - ~/.nvm/versions/node/v12.13.0/bin/npm Languages: Python: 2.7.17 - /usr/local/bin/python Browsers: Chrome: 81.0.4044.138 Edge: 81.0.416.72 Firefox: 74.0.1 Safari: 13.1 npmGlobalPackages: gatsby-cli: 2.12.31

NB I had to do the above manual install of detect-port to get this to work

[lukenetti3]

This exact same thing happened to me as well.

[valentinradu]

Same here. One quick fix is to install everything locally:

yarn add gatsby-cli
yarn add detect-port
npx gatsby help

or install detect-port globally:

yarn global add gatsby-cli
yarn global add detect-port
gatsby help