Web server failed to start. Port 6001 was already in use.

There could be a few reasons why the web server failed to start and port 6001 was already in use. Here are some steps you can take to troubleshoot the issue:

1. Check for any other processes using port 6001: Run the following command in your terminal or command prompt:

   lsof -i :6001

This will show you any processes currently using that port. You can then either stop the process or choose a different port for your web server.

2. Restart your computer: Sometimes, a reboot can help release any resources or ports that are being held by other processes.

3. Choose a different port for your web server: If port 6001 is consistently being used by another service, you can configure your web server to listen on a different port. Update your server configuration file (e.g., Apache's httpd.conf or Nginx's nginx.conf) with the new port and restart the server.

4. Check firewall settings: Ensure that your firewall is not blocking the port you are trying to use. You may need to add an exception or allow incoming connections to that port.

5. Verify if the port is being used by another service: You can use tools like netstat or TCPView to check if the port is being used by another application. If so, you may need to stop or reconfigure that application to free up the port for your web server.

By following these steps, you should be able to resolve the issue and start your web server successfully.