Software⏱️ 4 min read📅 2026-06-15

How to Fix: FTP Error: Upload failed 500 I won't open a connection to

Cyber Duck FTP error with proxy issue on hotel WiFi.

Quick Answer: Try using a different VPN client or configuring CyberDuck to bypass the proxy server.

📋 Table of Contents

  1. 🛑 Root Causes of the Error
  2. 🚀 How to Resolve This Issue
  3. ✨ Wrapping Up

FTP Error: Upload failed 500 I won't open a connection to (some ip) only to (other ip). This issue affects users who are trying to upload files using CyberDuck on their Mac devices while connected to hotel Wi-Fi. The problem arises when the user attempts to drag and drop a file for upload, resulting in a 500 error message.

This issue is frustrating because it prevents users from completing their file uploads, which can be critical for work or personal projects. To resolve this issue, we will explore two potential solutions: using a VPN to bypass hotel Wi-Fi proxy settings and checking the FTP port for blockage.

🛑 Root Causes of the Error

  • The primary reason for this error is that the hotel Wi-Fi uses a proxy server that blocks direct connections to the FTP server. When you try to upload files, CyberDuck attempts to connect directly to the FTP server, which is blocked by the proxy server, resulting in a 500 error message.
  • Another possible reason is that there might be issues with the HotSpot Shield VPN configuration or its compatibility with your hotel Wi-Fi network.

🚀 How to Resolve This Issue

Bypassing Hotel Wi-Fi Proxy Settings using VPN

  1. Step 1: Step 1: Install and configure a reliable VPN service on your Mac device. Ensure that the VPN connection is set to bypass the hotel Wi-Fi proxy settings.
  2. Step 2: Step 2: Connect to the VPN network before opening CyberDuck and attempting to upload files. This will help you bypass the hotel Wi-Fi proxy server and establish a direct connection to the FTP server.
  3. Step 3: Step 3: If you experience any issues with the VPN connection, try resetting the network settings on your Mac device or seeking assistance from the hotel's IT department.

Checking FTP Port Blockage

  1. Step 1: Step 1: Use CyberDuck to list the files in the directory without attempting to upload. This will help you determine if the issue is specific to uploading or if there are other problems with the connection.
  2. Step 2: Step 2: Check the FTP port (usually port 21) for blockage by using a tool like Telnet or Netcat on your Mac device. If the port is blocked, you may need to use an alternative FTP port (e.g., port 2121).
  3. Step 3: Step 3: If you suspect that the FTP port is blocked, try using an FTP client that supports multiple ports or contact your hotel's IT department for assistance in unblocking the port.

✨ Wrapping Up

To resolve the FTP error 'Upload failed 500 I won't open a connection to (some ip) only to (other ip)' when using CyberDuck on Mac devices connected to hotel Wi-Fi, try bypassing the hotel Wi-Fi proxy settings using a VPN or checking for FTP port blockage. By following these steps, you should be able to upload files successfully and avoid the 500 error message.

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