Resolving React Native Error: Yarn Not Recognized

The error message “yarn is not recognized as an internal or external command” is a common issue faced by developers working with React Native. This error typically occurs when the Yarn package manager is not installed correctly or its path is not set up properly in the system’s environment variables. Addressing this issue is crucial for ensuring smooth project setup and dependency management in React Native development.

Understanding the Error

The error message “yarn is not recognized as an internal or external command” typically appears when you try to run the yarn command in your terminal, but the system can’t find the Yarn executable. This usually happens because:

1. Yarn is not installed on your system.
2. Yarn is not added to your PATH environment variable, so the terminal doesn’t know where to find it.

To fix this, you need to install Yarn globally using npm install -g yarn and ensure your PATH environment variable includes the directory where Yarn is installed.

Common Causes

Here are the common causes of the “React Native error: ‘yarn’ is not recognized as an internal or external command”:

1. Missing Yarn Installation: Yarn is not installed on your system. Install it using npm install -g yarn.
2. Incorrect Path Configuration: Yarn’s executable path is not added to the system’s PATH environment variable.
3. Corrupted Yarn Installation: The Yarn installation is corrupted. Reinstall Yarn to fix this.
4. Terminal Issues: The terminal session needs to be restarted after installation or path configuration.

Step-by-Step Solutions

Sure, here’s a step-by-step guide to resolve the ‘yarn is not recognized as an internal or external command’ error:

1. Check Yarn Installation:

   yarn --version
   

   If you get a version number, Yarn is installed. If not, proceed to the next step.

2. Install Yarn Globally:

   npm install -g yarn
   

3. Verify Installation:

   yarn --version
   

   Ensure you see the version number.

4. Add Yarn to PATH (Windows):

   • Open the Start Menu, search for “Environment Variables”, and select “Edit the system environment variables”.
   • Click on “Environment Variables”.
   • In the “System variables” section, find and select the “Path” variable, then click “Edit”.
   • Click “New” and add the path to Yarn’s bin directory, typically:

     C:\Users\YOUR_USER\AppData\Roaming\npm
     

   • Click “OK” to save changes.

5. Restart Terminal:
   Close and reopen your terminal to apply the changes.

6. Run Yarn Command:

   yarn
   

7. Administrator Permissions (if needed):

   • Open Command Prompt as an administrator:
     • Search for “CMD” in the Start Menu.
     • Right-click “Command Prompt” and select “Run as administrator”.
   • Rerun the installation command:

     npm install -g yarn
     

8. Set Execution Policy (PowerShell):
   If you encounter a script execution error:

   Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
   

This should resolve the error and allow you to use Yarn with React Native.

Preventive Measures

1. Install Yarn globally: Run npm install -g yarn.
2. Add Yarn to PATH: Ensure Yarn’s installation directory is in your system’s PATH environment variable.
3. Restart terminal: After installation, restart your terminal to apply changes.
4. Use correct terminal: Use a terminal like Command Prompt, PowerShell, or a Unix-based terminal.
5. Keep Yarn updated: Regularly update Yarn with yarn upgrade.

Following these steps should help prevent the error from occurring.

To Resolve the ‘yarn is not recognized as an internal or external command’ Error in React Native

Follow these key steps:

1. Install Yarn globally using npm install -g yarn

2. Ensure Yarn’s installation directory is in your system’s PATH environment variable.

3. Restart your terminal after installation.

4. Use a correct terminal like Command Prompt, PowerShell, or a Unix-based terminal.

Regularly updating Yarn with yarn upgrade also helps prevent the error from occurring. Resolving this issue is crucial for ensuring smooth project setup and dependency management in React Native development.