zoom Code 104103

How to Fix Zoom Error 104103 (Network Connection Failure)

Diagnostic Procedures

  • 1 Understand the root cause of Zoom connection error 104103
  • 2 Verify network requirements and port access
  • 3 Clear cached Zoom files and reset app configurations
  • 4 Resolve firewall, security software, and VPN conflicts on Windows
  • 5 Resolve firewall, security software, and VPN conflicts on macOS
  • 6 Perform a clean reinstall of the Zoom desktop client

How to Fix Zoom Error 104103 (Network Connection Failure)

If you are experiencing Zoom Error Code 104103, it means the Zoom application is unable to establish a secure, stable connection with Zoom’s servers. This is classified as a network connectivity failure and usually prevents users from logging in, joining meetings, or starting a video stream.

This guide provides the technical explanations and exact step-by-step instructions to resolve this error on both Windows and macOS.

What Causes Zoom Error 104103?

Zoom Error 104103 triggers when the client attempts to reach the cloud server but is blocked or timed out during the network handshake. The primary root causes are:

  1. Firewall or Antivirus Blocks: The local security suite flag and prevent Zoom from sending or receiving data.
  2. Proxy and VPN Interference: Active VPN tunnels or proxy servers routing Zoom traffic through congested or restricted networks.
  3. Corrupted Network Stack: DNS cache corruption or incorrect Winsock routing tables preventing clean socket connections.
  4. Network Port Restrictions: Essential UDP and TCP ports required for Zoom transmission being blocked by the router or ISP.
  5. System Time Discrepancy: If your device time does not match internet time, secure SSL/TLS handshakes with Zoom servers will fail.

Technical Network and Port Requirements

To prevent communication drops, Zoom requires outbound access to the following ports. If you are on an enterprise network, ask your IT administrator to allow:

  • TCP Ports: 80, 443
  • UDP Ports: 3478, 3479, 5090, 5091, 8801 through 8810

Platform-Specific Resolving Steps

Follow the procedures below for your specific operating system to clear local network configurations and reset the Zoom client app.

Resolving Steps for Windows Users

1. Terminate All Running Zoom Processes

Lingering background processes can cause local port binding issues. Kill all active instances of the Zoom application using the Command Prompt:

taskkill /f /im Zoom.exe
taskkill /f /im ZoomOpener.exe

2. Flush DNS and Reset the Network Stack

Clear cached host resolution files and reset network interface card (NIC) routing tables:

ipconfig /flushdns
netsh winsock reset
netsh int ip reset

3. Allow Zoom Through Windows Defender Firewall

Ensure Windows Defender is not actively blocking Zoom’s network packets:

netsh advfirewall firewall add rule name="Zoom Video Conference" dir=in action=allow program="%appdata%\Zoom\bin\Zoom.exe" enable=yes
netsh advfirewall firewall add rule name="Zoom Video Conference" dir=out action=allow program="%appdata%\Zoom\bin\Zoom.exe" enable=yes

4. Clear Local Zoom App Cache Data

Clear corrupt temporary files cached within your local AppData directory:

rmdir /s /q "%appdata%\Zoom\data"
rmdir /s /q "%localappdata%\Zoom\logs"

Resolving Steps for macOS Users

1. Force Quit Zoom and System Openers

Ensure Zoom is completely shut down before initiating a network or client reset. Execute the following in Terminal:

killall zoom.us 2>/dev/null
killall "ZoomOpener" 2>/dev/null

2. Flush macOS DNS Cache

Reset your local DNS cache depending on your network settings:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

3. Delete Zoom Cache and Configuration Files

Clear cached sessions and preferences files that might store broken network routes:

rm -rf ~/Library/Caches/us.zoom.xos
rm -rf ~/Library/Application\ Support/zoom.us/data
rm -rf ~/Library/Logs/zoom.us
rm -rf ~/Library/Saved\ Application\ State/us.zoom.xos.savedState

4. Verify Active Proxy Configurations

Ensure your Mac is not routing traffic through an inactive proxy:

networksetup -getwebproxy "Wi-Fi"
networksetup -getsecurewebproxy "Wi-Fi"

(If a proxy is active and you are on a home network, disable proxies in System Settings > Network > Wi-Fi > Details > Proxies).

Perform a Clean Reinstall of the Zoom Client

If the network reset did not clear the 104103 error, the Zoom application files may be corrupted.

On Windows:

  1. Open the Run dialog (Win + R), type appwiz.cpl and press Enter.
  2. Locate Zoom in the list, right-click, and select Uninstall.
  3. Download and run the official installer from the Zoom Download Center.

On macOS:

  1. Open the Applications folder in Finder.
  2. Drag zoom.us to the Trash.
  3. Open Terminal and delete remaining traces: 
    rm -rf ~/Library/Application\ Support/zoom.us
  4. Download the latest version for macOS (ensuring you select the Apple Silicon version if using an M1/M2/M3 chip) and reinstall it.

Summary Checklist for Quick Reference

  • Verify Date/Time Sync: Ensure your system clock matches network time.
  • Disable VPN / Proxy: Temporarily disconnect VPN tunnels to see if direct routing fixes the error.
  • Disable Third-Party Antivirus: Temporarily disable third-party security applications (e.g., AVG, Avast) to check for firewall blockages.
  • Test Web Client: Attempt to join the meeting via the browser interface (zoom.us/join) to isolate application issues from general network issues.
  • Restart Network Hardware: Reboot your router or switch networks to a mobile hotspot to isolate ISP issues.