There are Modern Warfare data packs or add-ons installed on your Xbox that are incompatible with one another. In addition, the issue might have been brought on by a flawed game installation.

When trying to play Modern Warfare on Xbox, users are getting the dev error 603. The problem is not exclusive to any one Modern Warfare map, but rather affects nearly all of them.

First, you should see if the Modern Warfare game files are spread out across two drives (e.g., internal and external). Whether that’s the case, try moving your game’s data to the console’s internal storage and seeing if the problem still persists.

Dev Error 6034 XBox One


 Method 1: The Xbox’s Cache Must be Purged.

If the Xbox One’s cache is faulty, the dev error 6034 may appear in Modern Warfare. This issue may be remedied by erasing the Xbox’s cache.

  1. To completely turn off your Xbox, press the power button (till all lights are off).
  2. Remove the power supply by pulling the plug from the back of the Xbox and the wall outlet. Then, hold off for a minute.
  3. It’s time to reconnect the Xbox’s power cord to the wall outlet on its rear.
  4. Wait one more minute, or until the white light on the power brick on Xbox One (not S or X series) turns orange.
  5. Start the Xbox and see if the error 6034 has been fixed.

Method 2: Free Up the Game’s Reserved Area

The game may report dev error 6034 if it is unable to reach the allocated space where patches and updates are stored. In this case, the problem may be remedied by freeing up some of the Modern Warfare game’s allotted space.

  1. To access the menu in Modern Warfare on Xbox, move the cursor over it and select the Options button.
  2. The next step is to click on the Game and Add-ons Manager.
  3. Proceed to Saved Data, and then click Reserved Space in the left pane.
  4. To remove the reservation, use the Clear Reserved Space button and then confirm.
  5. Then, restart the console and see if the dev error 6034 has been fixed.

If it doesn’t work, head to the Modern Warfare Saved Data page (steps 1–3) and see assuming deleting the files there fixes the problem (if the game data are saved on the internal storage and game vault).

Method 3: Modify the Game System’s DNS Settings

If you’re getting the dev error 6034 in Modern Warfare, switching to OpenDNS or Google DNS may help. This could be because your console’s DNS settings are incorrect or inefficient.

  1. Select Settings by pressing the Xbox button on the controller.
  2. Get in there and click on Network in the new window that just popped up.
  3. To change your DNS settings, click the Advanced button.
  4. Choose Manual and then set the primary and secondary DNS as shown below.





Google DNS



4. Then, after making any necessary adjustments, click the Continue button to test the          DNS settings.

5. Now try running Modern Warfare to see if the error 6034 has been fixed.

Method 4: Take Down Game Updates and DLC

Because to potential incompatibilities between various Modern Warfare expansion packs and data, the game may crash with the dev error 6034. In this case, removing any expansions or data packs for the game could be the answer.

If you are prompted to buy the game after removing an add-on, try clearing the Xbox’s mac address (Settings > General > Network Settings > Advanced Settings > Alternative Mac address > Clear) and restarting the console.

  1. To access the game’s menu, move the cursor over Modern Warfare on Xbox and hit the Options button on your controller.
  2. Click the Game and Add-ons Manager menu item now.
  3. Then, head to your device’s settings, click the “Add-ons” tab, and deselect the following downloadable content packs (some may have different names depending on their size, for as “Compatibility Pack 2” may be labelled “Data Pack 2 (8 GB”)):

Call of Duty Modern Warfare MP2 Pack (size 9.1 GB)

Call of Duty Modern Warfare Multiplayer Pack 3 (Size 3.4 GB)

4. The next step is to save your changes and reboot the Xbox.

5. After powering the Xbox back on, see if the dev error 6034 has been fixed.

6. If the problem still persists, try uninstalling the following packs to see if it helps:

MP Pack 3 (3.4 GB)

Data Pack 2 (8.0 GB)

Campaign and Spec Ops Pack (14.8 GB)

MP Pack (9.1 GB)

Data Pack 1 (18.0 GB)

Survival Pack (5.9 GB)

High Res Pack 1 (23.6 GB)

Resolution Pack

7. Whether it doesn’t work, try uninstalling everything but the following packs to see if the      problem still persists.

Base Game (80.0 GB)

MP Pack (6.0 GB)

MP and SPEC Ops Pack (6.7 GB)

Campaign Pack (11.4 GB)

Spec Ops Pack (10.1 MB)

High Res Pack 3 (7.9 GB)

Operator Pack (10.1 MB)

Spec Ops Pack 1 (15.8 GB)

Spec Ops Pack 2 (2.5 GB)

High Res Pack 2 (9.9 GB)

Campaign Pack 2 (10.1 MB)

Campaign Pack 1 (10.1 MB)

MP Pack 2 (22.1 GB)

8. If it doesn’t work, try seeing if the problem goes away if you install nothing except the        following data and texture packs:

Multiplayer pack 2 (22.1 GB)

Multiplayer pack (6.0 GB)

Multiplayer and Special Ops pack (6.7 GB)

9. If the issue persists, check if reinstalling the Multiplayer pack (6.0 GB) solves the issue.

If the issue is still there, check if reinstalling the packs (mentioned in step 8) from the Store (not from the game) clears the dev error 6034.