How to Fix Dev Error 6034 on Xbox One in 6 Easy Methods (with Photos)

Key Points

• Dev Error 6034 is related to updated multiplayer data packs conflicting with old files in Call of Duty Modern Warfare.
• Uninstalling non-essential data packs, keeping only Multiplayer Pack 2, can fix the error.
• Hard rebooting the Xbox One or uninstalling and reinstalling the game may also resolve the issue.
• Changing the Xbox One’s MAC address or changing the NAT type to Open can help with internet-related issues.
• Power cycling the Xbox One can clear the system cache and improve performance.

You fire up your Xbox One, launch Call of Duty Modern Warfare, and the game gets stuck on the map loading screen. After a minute or so, the game crashes, and you are met with a “Dev Error 6034” message. The game is unplayable.

The error is incredibly frustrating and it seems to happen at random (and only to Modern Warfare 2019 and Warzone). Occasionally, the problematic map will load, and other times it will give you the error. What can you do to fix Dev Error 6034 on Xbox One?

In this article, we will share some solutions to fixing this error. Hang tight and follow along with us — you’ll be able to play Call of Duty again soon!

What is Dev Error 6034?

Dev Error 6034 seems to be related to updated multiplayer data packs conflicting with old files. The game tries to pull up files that no longer exist or are in the wrong location.

For some people, every map triggers the Dev error. For other people, only some game modes like Gunfight are unplayable. Since Call of Duty Modern Warfare doesn’t allow you to remove maps from matchmaking, you never know if you’ll get a map that triggers the error. The error also occurs across other platforms such as PC and PlayStation.

Now that we got that out of the way, let’s break down the different methods to get COD up and running again.

Method #1: Uninstall Multiplayer Data Packs

The best way to eliminate Dev Error 6034 on Xbox One is to uninstall the extra multiplayer data packs. One of these packs is likely causing the error. Most of the time, these extra data packs aren’t even required for multiplayer. You can always re-download the data packs later on.

Power on your Xbox One, head to My Games & Apps, and select Call of Duty Modern Warfare (or Warzone).

Next, press the menu button on your controller to open options. From there, select Manage game and add-ons. Deselect all non-essential data packs, Spec-ops packs, and anything else you don’t need.

Note: You’ll need to keep Multiplayer Pack 2 22GB, but you can delete the others.

Removing the following data packs should fix the Dev Error:

• Multiplayer Pack 3 3.4GB
• Multiplayer Pack 2 9.1GB

If that doesn’t work, delete the compatibility data packs. Keep in mind, sometimes there are two “Multiplayer Pack 2” files. In that case, uninstall the smaller version. The one you should uninstall is 9.1GB and the one you need is 22GB.

The names of the packs could be different too, depending on your version of the game. Either way, the file sizes should be the same, so uninstall any multiplayer pack that isn’t 22GB. If you already completed the campaign, you might as well uninstall it too.

Once all the data packs are deselected, press Save Changes to remove them from your Xbox One. Launch the game, and you should be free from Dev Error 6034!

If you uninstalled a data pack that is required for multiplayer, the game will automatically download it again. Besides fixing Dev Error 6034, uninstalling unnecessary data packs also frees up storage on your Xbox One.

Method #2: Hard Reboot Your Xbox One

If you uninstalled the unnecessary data packs and you’re still getting the error, you should hard reboot your Xbox.

There are two ways to hard reboot your Xbox One: pull the power cable or use the Full Shutdown option in the Power options.

To access Power options, open Settings, General, Power Options, and select Shutdown now.

When you reboot your Xbox One, the system should confirm the uninstalled files from earlier, and you should be free from Dev Error 6034.

Method #3: Uninstall and Reinstall Modern Warfare

Sometimes, uninstalling and reinstalling the entire game will fix Dev Error 6034. It’s not the most practical solution because the installation size for Call of Duty Modern Warfare can be 130GB. If your internet connection isn’t particularly fast, downloading the entire game might take a long time. Nevertheless, it often fixes the issues with conflicting game files.

To uninstall Call of Duty Modern Warfare, head to My Games & Apps, select the game, press the menu button on your controller, and select Uninstall All. Then, head back to your Full Game Library and start the download again.

Method #4: Use an Alternate MAC Address

If the problem is related to an internet issue, one fix could be configuring your Xbox One to use an alternate Mac Address. This can also help with internet connection issues such as slow download speeds.

To change your Xbox One’s Mac Address, head to Settings, Network Settings, Advanced Settings, and Alternate Mac Address.

When you change it, the Xbox will automatically reboot. You can also restart your router or modem. Once everything has been restarted, launch the game and see if the problem is gone.

Method #5: Change NAT Type to Open

When you launch Call of Duty Modern Warfare, you’ll see a message in the bottom right corner that shows your NAT Type. Ideally, it should be Open.

Changing the NAT Type to Open can be a little tricky because you need to open ports and some people are on shared networks that don’t allow port forwarding. For a full tutorial on how to change NAT Type on Xbox, visit this page.

Here’s a quick breakdown of how to change the NAT type on Xbox.

1. Access your router’s admin page (the most common is 192.168.0.1).
2. Locate the port forwarding options.
3. Add this port: TCP/UDP 3074.
4. Link it to your Xbox’s IP address.
5. Save the changes and reboot the router.

Method #6: Power Cycle Your Xbox

The last solution is to power cycle your Xbox One, it clears the system cache and can improve performance. Unplug your Xbox from the power, wait a minute, and then reconnect the power cable. This will force your Xbox to do a full shutdown.

For good measure, you can also press the power button on your console a few times while the cable is unplugged. We also recommend removing any USB devices that are connected to the Xbox.

Wrapping Up

The best way to fix Dev Error 6034 on Xbox One is to uninstall any non-essential Call of Duty data packs. The only data pack you need should be Multiplayer Pack 2, which is 22GB. The other ones are not essential. If you see another Multiplayer Pack 2 that is 9.1GB, uninstalling it should fix the issue. We would start by uninstalling the data packs and then move on to the other solutions.

When you complete all the solutions, 9 times out of 10, the Dev Error 6034 will be eliminated once and for all. If the problem persists, your only option is to submit a support ticket here or wait for an update to address the issue.

The image featured at the top of this post is ©Anthony McLaughlin/Shutterstock.com.