How to Fix Diablo 4 Error Code 401003

By Lidia Rozo | 2023-06-07 01:42:43
Check out our guide on how to fix Diablo 4 error code 401003 and get back to the game in no time.
Diablo 4 is one of the most popular action role-playing games of all time. However, some players have recently reported encountering an error code 401003 while trying to play the game. This error can be frustrating and make it impossible to play the game. Fortunately, there are steps you can take to fix the error code and get back to playing Diablo 4. In this blog post, we will discuss some of the most effective solutions to fix Diablo 4 error code 401003.

Update your network driver


One of the most common causes of Diablo 4 error code 401003 is an outdated network driver. Updating your network driver can help to fix this issue. A network driver is a software program that allows your computer to communicate with your network adapter. If your network driver is outdated, it may not be able to handle the communication required to play Diablo 4.
To update your network driver, follow these steps:
  • 1. Open the Device Manager on your computer.
  • 2. Expand the Network adapters category.
  • 3. Right-click on your network adapter and select Update driver.
  • 4. Follow the on-screen instructions to update your network driver.

Temporarily disable Windows Firewall



Another solution to fix Diablo 4 error code 401003 is to temporarily disable Windows Firewall. Windows Firewall is a security feature that helps to protect your computer from unauthorized access. However, sometimes it can block Diablo 4 from communicating with the internet, which can cause the error code.

To disable Windows Firewall, follow these steps:

  • 1. Open the Control Panel on your computer.
  • 2. Click on System and Security.
  • 3. Click on Windows Defender Firewall.
  • 4. Click on Turn Windows Defender Firewall on or off.
  • 5. Select Turn off Windows Defender Firewall (not recommended) for both private and public networks.
  • 6. Click on OK to save the changes.

 Flush DNS cache

One possible cause of Diablo 4 Error Code 401003 is a problem with your DNS cache. DNS cache is a temporary database that stores information about domain names and their corresponding IP addresses. If your DNS cache contains outdated or incorrect information, it can cause connection problems.

Flushing your DNS cache can help fix the problem. This will clear the cache and force your computer to look up the correct IP addresses. Here's how to do it:

  • 1. Open the command prompt by searching for "cmd" in the Start menu.
  • 2. Right-click on the Command Prompt app and select "Run as administrator".
  • 3. Type the following command: ipconfig /flushdns
  • 4. Press Enter.
  • 5. Wait for the process to complete (it should only take a few seconds).
  • 6. Restart your computer.

After restarting your computer, try launching Diablo 4 again and see if the error code has been resolved.


 Enable UPnP


Another possible cause of Diablo 4 Error Code 401003 is a problem with UPnP. UPnP stands for Universal Plug and Play, and it allows devices to discover and communicate with each other on a network. If UPnP is disabled or not working correctly, it can cause connection problems.

Enabling UPnP can help fix the problem. Here's how to do it:

  • 1. Open your router's web interface by typing its IP address into your web browser (usually 192.168.1.1 or 192.168.0.1).
  • 2. Log in to your router using your username and password.
  • 3. Look for the UPnP option in the router's settings (it may be under "Advanced" or "Network").
  • 4. Enable UPnP.
  • 5. Save your changes and exit the router's settings.

After enabling UPnP, try launching Diablo 4 again and see if the error code has been resolved.

 Forward ports


A third possible cause of Diablo 4 Error Code 401003 is a problem with port forwarding. Port forwarding is a technique that allows incoming traffic to reach your network devices. If port forwarding is not set up correctly, it can cause connection problems.

Forwarding the necessary ports can help fix the problem. Here's how to do it:

  • 1. Open your router's web interface by typing its IP address into your web browser (usually 192.168.1.1 or 192.168.0.1).
  • 2. Log in to your router using your username and password.
  • 3. Look for the Port Forwarding option in the router's settings (it may be under "Advanced" or "Network").
  • 4. Add the following ports to the list of forwarded ports: 3724, 1119, and 6881-6999.
  • 5. Save your changes and exit the router's settings.

After forwarding the necessary ports, try launching Diablo 4 again and see if the error code has been resolved.

Diablo 4 error code 401003 can be frustrating, but there are steps you can take to fix it. Updating your network driver, disabling Windows Firewall, flushing DNS cache, enabling UPnP, and forwarding ports can all help to resolve the issue. If none of these solutions work, you may need to contact Blizzard support for further assistance.
Tags: Diablo IV, action RPG, dungeon crawler, loot-driven, dark fantasy, character classes, skill trees, endgame content, worl
Platform(s): Xbox One, Xbox Series X/S, PlayStation 4, PlayStation 5, Microsoft Windows
Genre(s): Action role-playing, hack and slash
Developer(s): Blizzard Team 3, Blizzard Albany
Publisher(s): Blizzard Entertainment
Release date: June 6, 2023
Mode: Single-player, multiplayer
Age rating (PEGI): 18+
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