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

What Causes Dev Error 6034 on Xbox One Call of Duty?

Dev Error 6034 is one of the most frustrating issues in Call of Duty: Modern Warfare and Warzone on Xbox consoles. When the error appears, the game often crashes or gets stuck on the loading screen for multiplayer maps.

According to analysis by tech professionals, Dev Error 6034 stems from conflicts between old and newly updated multiplayer data packs. The game tries to load outdated files that no longer exist in the expected location. This causes a crash and the cryptic developer error code.

The problem can occur randomly and inconsistently. Sometimes a certain map will load fine, while other times it triggers the crash. Since Modern Warfare doesn‘t allow players to toggle maps on and off for matchmaking, there is no way to avoid problematic maps.

Method #1: Uninstall Extra Multiplayer Data Packs

The most reliable fix for Dev Error 6034 is to remove all non-essential multiplayer data packs. Here‘s how:

  1. On your Xbox One dashboard, highlight Call of Duty: Modern Warfare/Warzone and press the menu button.
  2. Select Manage Game and Add-ons.
  3. In the list of installed data packs, deselect and uninstall anything except Multiplayer Pack 2 (22GB).
call of duty manage addons

The additional multiplayer packs with these filenames often cause Dev Error 6034:

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

So make sure you keep only the 22GB version of Multiplayer Pack 2.

  1. After deselecting the problematic data packs, press Save Changes. The packs will uninstall automatically.

This method resolves the error by removing the outdated multiplayer files that conflict with updated ones. If any required packs get deleted, the game will simply redownload them when you try to play multiplayer.

You can also free up storage space in the process by removing unneeded packs like Special Ops, Campaign, etc.

Method #2: Hard Reboot Your Xbox One

If you still get Dev Error 6034 after removing the extra multiplayer packs, try rebooting your Xbox One. This will force the system to recheck your installed addons and confirm the file removals.

To hard reboot properly:

  1. Fully power down your Xbox One using either the on-screen Shut Down option or by unplugging the power cable.

  2. Wait at least 30 seconds with the Xbox powered off.

  3. Turn your Xbox back on and try loading Call of Duty again.

This often resolves any lingering issues with corrupted data caches or improper shutdowns that could contribute to the error.

hard reboot xbox

Method #3: Uninstall and Reinstall Call of Duty

If you still see Dev Error 6034, your next course of action should be deleting Call of Duty entirely and redownloading a fresh copy. This ensures all old corrupted files get removed.

To uninstall and reinstall:

  1. Go to My Games and Apps > Call of Duty Modern Warfare/Warzone.
  2. Press the menu button and select Uninstall All.
  3. After it completes, go back to your Xbox dashboard and redownload Call of Duty.

Yes, redownloading the 100+ GB game takes a long time. But once finished, you should have a clean updated copy that gets rid of the errors.

Method #4: Switch to Alternate MAC Address on Xbox

Some cases of Dev Error 6034 relate to networking issues between your Xbox One and the internet/servers. Switching to an alternate MAC address can often resolve problems like this.

MAC stands for Media Access Control and it functions like an identification number for network connections. Follow these steps to change it:

  1. From your Xbox One settings, go to Network > Network Settings > Advanced Settings.
  2. Select Alternate MAC Address.
  3. Click Clear > Restart.

This wipes your Xbox‘s current MAC address and issues a new one after rebooting. It essentially tricks the network into thinking it‘s connecting to a new device.

Try loading Call of Duty after this process completes. There‘s a good chance Dev Error 6034 will disappear.

Method #5: Forward Ports and Enable UPnP for Open NAT

Another networking tweak that could fix Dev Error 6034 is getting your Xbox One into an Open NAT type with proper port forwarding.

NAT stands for Network Address Translation and refers to how your Xbox One interacts with routers to connect to the internet. Open is the best NAT type for stable online gaming.

Here‘s how to enable UPnP and forward ports on your router:

  1. Login to your router‘s configuration page, usually at http://192.168.0.1 or http://192.168.1.1.
  2. Navigate to the Port Forwarding or UPnP/NAT-PMP section.
  3. Enable UPnP and add a new TCP/UDP port forwarding rule:
    • Service Name: Xbox One
    • External Port: 3074
    • Internal Port 3074
    • Protocol TCP/UDP
    • Device IP: your Xbox One‘s IP (find it in Settings > Network)
  4. Save settings and reboot your router.

After this your Xbox should pull an Open NAT type automatically in its network test screen. Loading up Call of Duty again may resolve Dev Error 6034.

open NAT type

Method #6: Power Cycle Your Xbox

The last recommendation is power cycling your Xbox One. This clears system caches similar to a hard reboot, but takes it further by powering down and restarting multiple times in a row.

Follow these steps:

  1. Hold down the power button on your Xbox console until it fully shuts down.
  2. Unplug the power cable and wait 60 seconds.
  3. Plug the power back in and press the Xbox power button again while booting up. Let it fully start.
  4. Repeat steps 1-3 two more times.

On the 3rd restart, your Xbox One will boot up fresh with cleared system caches that were causing stability/performance issues leading to Dev Error 6034 crashes.

Summary of Fixes for Dev Error 6034 Xbox One

Method #1 Uninstall Extra Multiplayer Data Packs
Method #2 Hard Reboot Your Xbox One
Method #3 Uninstall and Reinstall Call of Duty
Method #4 Switch to Alternate MAC Address on Xbox
Method #5 Forward Ports and Enable UPnP for Open NAT
Method #6 Power Cycle Your Xbox

Now that you know what causes Dev Error 6034 and multiple proven methods to resolve it, Call of Duty gaming on your Xbox One should be back up and running smoothly.

The key is removing those problematic multiplayer packs and then taking further steps from rebooting, reinstalling or tweaking network settings. But in most cases, simply deleting the bad data packs does the trick.

If you still face issues after trying everything, you‘ll need to contact Activision Support directly or wait for patches. But more often than not, one of these 6 fixes will banish Dev Error 6034 for good. Game on!

Frequently Asked Questions

Why does Dev Error 6034 happen on Xbox One?

The error stems from outdated multiplayer data packs conflicting with updated ones. When the game tries to pull files that no longer exist, it crashes and shows Dev Error 6034.

Will reinstalling Call of Duty fix the Xbox crash error?

Yes, deleting all files and reinstalling a fresh clean copy can resolve conflicts with corrupt/missing data packs causing the crashes.

Does changing NAT type or MAC address help Dev Error 6034?

Sometimes. If the crashes relate to networking problems, an alternate MAC and open NAT type improves connectivity between your Xbox and the game servers.

How do I stop Call of Duty from crashing on Xbox One?

The number one method is removing all non-essential multiplayer packs under the game‘s Manage Add-Ons menu. Multiplayer Pack 2 (22GB) should fix crashing.

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