> ## Documentation Index
> Fetch the complete documentation index at: https://docs.intuitibits.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting

> Troubleshoot connection issues in Transfer.

If you're having problems connecting to *Transfer*, make sure the file transfer protocol you're using is enabled (*Transfer* > *Settings* > *General*) and that no firewall is blocking access to *Transfer* on your Mac.

Also, if you're trying to connect with an HTTP, HTTPS, FTP or SFTP client, make sure the client is using the correct username or password (*Transfer* > *Settings* > *General*).

If you need more details about file transfers and connection attempts, choose *View* > *Show Logs* or Command-L. In addition to information and error messages, you can also enable debug messages by choosing *Help* > *Enable Debug*.

***

## Resolve a "port already in use" error

If a protocol's status shows *Unable to listen for \[protocol] requests: port \[number] already in use*, another server on your Mac is already using that port. *Transfer* listens on the following ports by default:

| Protocol | Default Port |
| -------- | ------------ |
| TFTP     | UDP 69       |
| HTTP     | TCP 80       |
| FTP      | TCP 21       |
| SFTP     | TCP 22       |

macOS includes built-in servers for TFTP, HTTP, FTP, and SFTP that may already be running and holding the port. To free it up:

### TFTP

Open Terminal and run:

```bash theme={null}
sudo launchctl stop com.apple.tftpd
sudo launchctl unload -F /System/Library/LaunchDaemons/tftp.plist
```

### HTTP

Open Terminal and run:

```bash theme={null}
sudo launchctl unload -w /System/Library/LaunchDaemons/org.apache.httpd.plist
```

### FTP

Go to *System Settings* > *General* > *Sharing* and turn off **File Sharing**, or open its options and deselect FTP access.

### SFTP

Go to *System Settings* > *General* > *Sharing* and turn off **Remote Login**.

<Tip>
  If none of the built-in servers are the cause, a third-party application may be using the port instead. Check that application's documentation for how to disable it.
</Tip>

Once the port is free, click **Retry** next to the affected protocol in *Transfer*.

## See also

* [Change General settings](/transfer/general-settings)
* [FAQ](/transfer/frequently-asked-questions)