Web server failed to start. Port 8181 was already in use.

There could be several reasons why the web server failed to start and encountered a port conflict. Here are a few troubleshooting steps you can try:

1. Check for running processes: Run the following command in your terminal to check if any process is currently using port 8181:

   lsof -i :8181

If you get any output, it means another process is already using that port. You can then terminate that process or choose a different port for your web server.

2. Use a different port: If port 8181 is already in use, you can try starting the web server on a different port. Update the configuration file of your web server to listen on a different port and restart the server.

3. Restart your machine: Sometimes, a port conflict can be resolved by simply restarting your machine. After the reboot, try starting the web server again on port 8181.

4. Check firewall settings: Ensure that there are no firewall rules blocking incoming connections on port 8181. Adjust your firewall settings accordingly to allow traffic on that specific port.

5. Kill the process manually: If none of the above steps work, you can force kill the process using the following command:

   kill $(lsof -t -i:8181)

This will terminate any process that is currently using port 8181.

Remember to adapt these steps to your specific operating system and web server configuration.