There are Modern Warfare data packs or add-ons installed on your Xbox that are incompatible with one another. Moreover, the issue might have been brought on by a faulty installation of the game.
When attempting to play Modern Warfare on Xbox, users are getting the dev error 603. This is not a problem exclusive to any one Modern Warfare map, but rather an issue that occurs on nearly all of them.
Method 1: Delete the Xbox’s Temporary Files.
If the Xbox One’s cache is faulty, the dev error 6034 could appear in Modern Warfare. Potentially resolvable by erasing all game data from the Xbox’s storage device is the current situation.
Step 1: To completely turn off your Xbox, press the power button (till all lights are off).
Step 2: Disconnect the Xbox’s power cord from the wall outlet and the console’s rear. Then, hold on for a minute.
Step 3: Reconnect the Xbox’s power cord to its socket on the console’s back.
Step 4: Then wait one more minute, or until the white light on the power brick turns orange if you’re using an original Xbox One (not the S or X series).
Step 5: Restart the Xbox and see if the error 6034 has been fixed.
Method 2: Get Out of The Game’s Reserved Area!
However, if the game is unable to access the allocated area, which is required to store patches and updates, the dev error 6034 will be displayed. In this case, the problem may be remedied by freeing up some of the Modern Warfare game’s allotted space.
Step 1: To access the menu in Modern Warfare on Xbox, mouse over the game and press the Options button.
Step 2: Click on the Game and Add-ons Manager option now.
Step 3: After that, select Reserved Space from the list of options on the left side of the screen under Saved Data.
Step 4: To remove the reservation, click the Clear Reserved Space button and then confirm.
Step 5: After the console has restarted, you may see if the dev error 6034 has been fixed.
If it doesn’t work, go to Modern Warfare’s Saved Data tab (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
Changing your console’s DNS settings to OpenDNS or Google DNS may resolve the dev error 6034 in Modern Warfare if they were improperly configured.
Step 1: To access the configuration menu, press the Xbox button on the controller.
Step 2: A new menu will appear; select Network from this menu.
Step 3: To change your DNS settings, click the Advanced button.
Step 4: Next, choose Manual and provide the following information for the primary and secondary DNS servers:
OpenDNS
Primary: 208.67.222.222
Secondary: 208.67.220.220
And
Google DNS
Primary: 8.8.8.8
Secondary: 8.8.4.4
Step 5: After making any necessary adjustments, select Continue to test the DNS settings.
Step 6: The error 6034 should now be gone, so try starting Modern Warfare to see if it still occurs.
Method 4: Completely Reinstall the Modern Warfare Game
If the installation of Modern Warfare on Xbox is corrupt, you may see the dev error code 6034. If this happens, try reinstalling the game. The operation is time-consuming because there is over 200 GB of data to download. Make a copy of your game’s save file before continuing.
Step 1: Xbox Settings Game Library Games Modern Warfare.
Step 2: Next, select Uninstall from the menu.
Step 3: If you’re sure you want to remove Modern Warfare, you may do so by selecting Uninstall All and waiting for the process to finish.
Step 4: After you have removed Modern Warfare, restart your console and install it again, but this time only install the following:
Modern Warfare Base Game
Multiplayer pack 2 (22.1 GB)
Multiplayer pack (6.0 GB)
Multiplayer and Special Ops pack (6.7 GB)
Step 5: To see if the dev error 6034 has been fixed, start the game now.
