Yarn error: Command failed with exit code 127 [Solved]

# Yarn error: Command failed with exit code 127 [Solved]

The yarn error "Command failed with exit code 127" most commonly occurs when you forget to install the modules before running your yarn commands.

To solve the error, run the yarn install command before running yarn start.

Open your terminal in your project's root directory (where your package.json file is) and run the following command.

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yarn install

You can also use the yarn command to install all modules that are stored in your package.json file.

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yarn

Try to start your development server after running yarn install.

You can view your start command in the scripts section of your package.json file.

It might look similar to the following:

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{
  "scripts": {
    "start": "react-scripts start"
  }
}

If the command that starts your development server is named start, then run the yarn start command.

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yarn start

You can also install your modules and run the yarn start command in a single go.

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yarn install && yarn start

If it is named dev, then you would run yarn dev.

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yarn dev

If you need to build your project for deployment, the command will likely be yarn build.

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yarn build

# Delete node_modules and rerun yarn install

If the error persists, delete your node_modules directory and rerun yarn install.

Open your terminal in your project's root directory (where your package.json file is).

If you are on Windows, run the following commands in CMD.

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# for Windows
rd /s /q "node_modules"

# 👇️ clean your yarn cache
yarn cache clean

# 👇️ install packages
yarn install

If you are on macOS or Linux, run the following commands in bash or zsh.

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#  for macOS and Linux
rm -rf node_modules

# 👇️ clean your yarn cache
yarn cache clean

# 👇️ install packages
yarn install

Try to start your development server after reinstalling your modules.

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yarn start

# OR if your script is named `dev`
yarn dev

# Make sure the folders in your project's path don't contain spaces or special characters

Another common cause of the error is when the folders in your project's path contain spaces or special characters.

Make sure none of the folders in your project's path contain:

• spaces.
• hash symbols #, colons :, dollar signs $, etc.

The issue is caused if any of the folders in the path contain spaces or special characters, not just your root project folder.

I've also written an article on how to force yarn to reinstall a package.