How to Fix Dev Error 6661 in COD: Warzone?

Dev error 6661 might occur due to configuration issues of Warzone or a corruption of the game or the OS. The configuration issues range from command line arguments to the XMP/D.O.C.P profile of the BIOS. The dev error is reported on nearly all Warzone-supported platforms. The error occurs when the Warzone game crashes with dev error 6661.

Dev Error 6661

You may encounter the dev error 6661 on Warzone mainly due to the following factors:

  • Outdated Game, System’s BIOS, or Drivers: You may encounter the dev error 6661 on Warzone if the game itself, system’s BIOS, or drivers are outdated as it can create incompatibility between the OS applications like Warzone.
  • Corrupt Temporary Files of the System: If the temporary files directory on your system is corrupt, then that may result in dev error 6661 on Warzone as the game stores many of its temporary files in this directory and its corruption may not let the game access the required files.
  • HDR Feature of the Console: HDR feature of a console helps greatly enhance the display quality of the game but it can sometimes glitch out the game’s graphics and thus cause the issue at hand.
  • Corrupt Installation of the Warzone Game: You may encounter the issue under discussion if the game’s installation itself is corrupt as it can hinder the game’s ability to load essential modules.

1. Update the Warzone Game to the Latest Build

You may encounter the dev error 6661 if the installation of the Warzone game is outdated which may cause incompatibility between the OS and game as the game may fail to access the required system modules. Here, updating the Warzone game to the latest build may solve the problem.

  1. Launch the Battle.net app and open Warzone.
  2. Now expand the game’s Options of the Warzone and in the menu shown, click on Check for Updates.
    Check for Call of Duty Warzone’s Updates
  3. If a game update of the Warzone is available, download and install the update.
  4. Once the Warzone is updated, relaunch the Battle.net client, and afterward, check if Warzone is clear of the dev error 6661.

2. Update the System’s Drivers to the Latest Build

If the system’s drivers are outdated, then their incompatibility with the Warzone game may not let the game properly execute its essential modules, resulting in the dev error 6661. In this context, updating the system’s drivers to the latest build may resolve the Warzone issue.

  1. Update the system’s drivers (especially, graphics and PCI-E drivers) to the latest build. If you have an OEM utility like Dell Support Assistant, it will be better to use that utility to update the system’s drivers.
  2. Once the system’s drivers are updated, launch Warzone and check if it is working fine.

3. Remove Command Line Argument of Warzone in the Battle.net Client

You may encounter the dev error 6661 if you have configured Warzone to launch in DirectX 11 by using the Command Line Agreement as that may cause the incompatibility between the game and the old DirectX modules. Here, removing the Command Line Argument of Warzone to launch it in the latest DirectX modules may solve the problem.

  1. Launch the Battle.net app and choose Warzone.
  2. Now click on the Settings icon and choose Game Settings.
    Remove Additional Command Line Arguments of Warzone
  3. Then delete the argument (like -d3d11) in the Command Line Argument and untick the option of Command-Line Argument.
  4. Now apply the changes made and launch Warzone to check if it is clear of the dev error 6661.

4. Change Emblem and Calling Card in the Warzone

Calling cards or emblem is used by players to customize their appearances in the COD games. If the calling card or emblem modules of the Warzone are glitched out, then that may cause the dev error 6661. Here, changing the emblem or calling card of the player may solve the problem.

  1. Launch Warzone Options in the Battle.net app and steer to the Barracks tab.
  2. Then, on the left-hand side of the window, choose Calling Cards and make sure Randomize Favorites or Randomize All are not selected.
    Open Calling Card and Emblems in the Barracks Tab of Warzone Options
  3. Now choose a different calling card (single) and then, repeat the same within the Emblems tab.
  4. Now launch Warzone and check if it is clear of the dev error 6661.
  5. If not, check if changing your favorite loadout/gun to a Modern Warfare weapon (if a Cold War weapon is selected) and setting it to use default skin resolves the issue.
  6. If the issue persists, change your player’s skin to a Modern Warfare operator and then check if that clears out the Warzone dev error 6661.
  7. If that did not work, check if reverting all the vehicles’ skins, music, and horns to their defaults resolves the Warzone issue.

5. Open the Battle.net App and Warzone Game as an Administrator

If Warzone does not have administrative privileges to access the protected system resources that are essential for the game, then that may result in dev error 6661. In this context, launching the Battle.net app and Warzone game as administrator may solve the dev error.

5.1 Launch the Battle.net Client as Administrator

  1. Right-click on the Battle.net icon on the desktop shortcut and select Run as Administrator.
    Open the Battle net App as an Administrator
  2. Now select Warzone and click on the Play button.
  3. Afterward, check if the Warzone game is operating normally.

5.2 Launch Warzone as Administrator

  1. If the issue persists, launch the system’s Task Manager and make sure to end all Warzone-related processes (Battle.net client and Warzone’s processes).
    End Tasks of Blizzard Battle net App
  2. Now, launch the Battle.net app as administrator (discussed earlier) and choose Warzone.
  3. Now click on Settings and in the menu shown, select Show in Explorer.
    Show Warzone in Explorer
  4. Then, in the File Explorer window, right-click on Modern Warfare Launcher.exe and click on Run as Administrator.
    Launch Warzone as Administrator from the Installation Directory
  5. Now wait for a few seconds and afterward, right-click on the ModernWarfare.exe file.
  6. Then choose Run as Administrator and once Warzone is launched, check if it is clear of the dev error 6661.

5.3 Set the Battle.net Client, Warzone, and Related Processes to Open as Administrator

If the issue was resolved after launching the Warzone game or Battle.net launcher as administrator, then to make the process permanent, you may follow the steps below:

  1. Close Warzone and exit the Battle.net app.
  2. Then end all the Warzone-related processes in the Task Manager of your system.
  3. Now, right-click on the shortcut of the Battle.net app and choose Open File Location.
    Open File Location of the Battle.net Client
  4. Afterward, in the File Explorer window, right-click on the Battle.net Launcher.exe file and choose Properties.
  5. Then steer to the Compatibility tab and tick the checkbox of Run This Program As An Administrator.
    Enable Run This Program as an Administrator for Battle.net
  6. Now Apply the changes and afterward, repeat the same to the Battle.net.exe file.
  7. Once done, launch the Battle.net client and choose Warzone.
  8. Now click on Settings and choose Show in Explorer.
  9. Then right-click on modernwarfare launcher.exe and select Properties.
  10. Now head to its Compatibility tab and tick the checkbox of Run This Program as Administrator.
  11. Then apply the changes and repeat the same for modernwarfare.exe.
    Open ModernWarfare.exe as Administrator
  12. Now launch Warzone through the Battle.net launcher and check if its dev error is cleared.

6. Delete the Temporary Files of the System

Temporary files on a system hold temporary data about different applications or games like Warzone. If these files are corrupt, then that corruption might lead to the dev error at hand as the game may fail to access the temporary files essential for its operation. In this case, you may fix the dev error 6661 by deleting the contents of the Temporary Files directory of the system.

  1. Close the Warzone game and exit the Battle.net app.
  2. Now, right-click Windows and open Run.
    Open the Run Command Box from the Quick Access Menu
  3. Then navigate to the following path:
    %temp%
    Open %Temp% Directory
  4. Now delete all the contents of the directory and ignore the files/folders that you cannot delete.
    Delete the Files in the Percent Temp Folder
  5. Once done, navigate to the following path in the Run command box:
    temp
    Delete the Contents of the Windows Temp Folder
  6. Then delete all the contents of the temp directory and ignore the files/folders that cannot be deleted.
  7. Now restart the system and upon restart, launch Warzone and check if it is operating fine.

7. Optimize the Graphics Settings of the Warzone

You may encounter the dev error 6661 on Warzone if the game is not running in the optimal graphics settings as the parsing of the video codecs may glitch out and thus cause the issue. Here, optimizing the graphics settings of the Warzone through the graphics application (like Nvidia GeForce Experience) may solve the problem.  

  1. Close the Warzone game and its launcher.
  2. Now end the Warzone-related processes in the PC’s Task Manager.
  3. Then launch Nvidia GeForce Experience and head to its Games tab.
  4. Now select Warzone and on the right side of the window, click on Optimize.
    Optimize Warzone in GeForce Experience
  5. Once done, launch the game and check if the Warzone’s dev error 6661 is cleared.
  6. If not, head to 3D Settings in the Nvidia Control Panel and open Manage 3D Settings.
  7. Now select Low Latency Mode and under the Global Settings tab, disable it by selecting off in the dropdown. 
    Disable Low Latency Mode of the Nvidia Card
  8. Then launch Warzone and check if it is operating fine without error 6661.
  9. If that did not work, check if disabling Nvidia Game Filters resolves the issue.
  10. If the issue persists, check if disabling Sun n Shadow cache solves the Warzone problem.
    Disable Sun n Shadow Cache of Nvidia
  11. If not, check if restarting the shader’s cache resolves the problem.
    Restart Shaders Installation of the Modern Warfare

8. Disable Adaptive Sync/ G Sync/ Free Sync

Adaptive Sync, G Sync, or Free Sync is the technology used to match the display’s refresh rate with the GPU and thus avoid tearing of the display on the screen. Despite its usefulness, sometimes, this technology may hinder the graphic rendering of the Warzone game on your system and thus cause the dev error 6661. In this scenario, disabling adaptive sync, G Sync, or Free Sync through the graphics utility may solve the problem. For illustration, we will discuss the process of disabling G-Sync for an Nvidia card.

  1. Close the Warzone game and exit the game’s launcher.
  2. Now launch the NVIDIA control panel and on the left-hand side of the NVIDIA control panel, expand the Display tab.
  3. Then steer to the Setup G-Sync tab and on the right-hand side of the window, untick the checkbox of Enable G-Sync.
    Disable G-Sync
  4. Now apply the changes and launch Call of Duty Warzone to check if it is clear of the dev error 6661.

9. Change the Video Memory Scale Value of the Warzone Game

Video Memory Scale is the scaling factor for how much of the available VRAM is used when Warzone is running. If the system is running low on the VRAM and fails to locate the RAM required by Video Memory Scaling of the Warzone, then that may glitch out the game’s graphics, leading to the dev error 6661. Here, changing the Video Memory Scale value of the Warzone may solve the Warzone problem.

  1. Make sure to exit the Warzone game along with its launcher and end the game-related processes in the system’s Task Manager.
  2. Then right-click Windows and select Run.
  3. Now navigate to the following path:
    Documents
    Open Documents Folder Through the Run Command Box
  4. Then open the Call of Duty Modern Warfare folder and double-click on Players.
  5. Now right-click on adv_options.ini and select Open With>> Notepad.
    Open Adv_Options.ini File in Notepad
  6. Then search for VideoMemoryScale and set its value to 0.45.
    Set VideoMemoryScale of Warzone to 0.45
  7. Now save the changes and close Notepad.
  8. Then launch Warzone through the Battle.net client and check if the game is clear of the error 6661.
  9. If that fails, check if setting the value of VideoMemoryScale to 0.6 solves the problem.
  10. If that did not work, check if lowering the RenderingWorkerCount to half of the physical cores of your system resolves the issue e.g., if your system has 4 cores, set RenderingWorkerCounto to 2.
  11. If not, exit the Warzone game and steer to the Documents directory of the system.
  12. Now rename the Call of Duty folder to reset the game’s configurations to its defaults and then launch Warzone to check if it is clear of the dev error 6661.

10. Disable HDR on the Console

High Dynamic Range (HDR) is used to enhance brightness and vibrant colors on your screen by emphasizing various elements. If your console has an HDR feature (like an X series Xbox) and is enabled, then the HDR’s display manipulation might cause a glitch in the Warzone graphics parsing and thus cause the dev error 6661. In this context, disabling HDR on the console may solve the Warzone problem.

  1. Power on the Xbox (if powered off) and press the X key on the controller.
  2. Now open Power & System and select Settings.
  3. Then open General and select TV and Display Options.
    Open TV & Display Options in the General Tab of Xbox Settings
  4. Now open Video Modes and uncheck Auto HDR.
    Disable HDR in the Xbox Video Modes
  5. Then restart your console and upon restart, launch Warzone to check if its dev error 6661 is cleared.

11. Perform a Clean Boot of the System

Warzone might crash with dev error 6661 if another application on the system is hindering the essential Warzone modules and not letting them execute properly. In this context, performing a clean boot of the system may clear the dev error 6661.

  1. Firstly, check if the Warzone works fine in the Safe Mode of your PC.
  2. If so, perform a clean boot of your PC and check if the Warzone is operating normally.
    Clean Boot the Windows 10 PC
  3. If so, then enable back the services/processes/applications (one by one) disabled during the clean boot process and find the culprit causing the issue. Riva Tuner is a reported application to crash Warzone with dev error 6661 and if you have it (or something similar) on your system, then you may uninstall it to solve the problem.
  4. If the Warzone did not work on step 2, perform a clean boot of the system but leave only Battle.net, the system’s AV, and drivers enabled, and then check if that resolves the issue.
  5. If the issue persists, power off the router and disconnect all the devices (like a Chromecast) from the router.
  6. Now power on the router and make sure only your system or console is connected to the router.
  7. Then check if Warzone has started to work fine. If so, then another device on your network is causing the issue and you may resolve the issue with that device. 
  8. If the issue was not resolved, make sure the Warzone required ports are properly forwarded in the router’s settings and then check if the Warzone dev error 6661 is cleared.

12. Scan and Repair the Warzone Installation

Warzone might show the dev error 6661 if its installation is corrupt and due to this corruption, the game is failing to load the essential game modules. In this case, scanning and repairing the Warzone installation may clear the error 6661.

  1. Open the Battle.net client and in the game’s library, choose Warzone.
  2. Now click on Settings and in the dropdown menu, select Scan and Repair.
    Scan and Repair Warzone
  3. Then wait till the process completes (it can take some time) and once done, relaunch the Battle.net app and check if dev error 6661 is cleared.
  4. If not, check if launching the Warzone in full screen borderless solves the problem.

13. Disable XMP or DOCP Profile in the System’s BIOS

Intel Extreme Memory Profile (XMP) is a simple method to run the system in its overclocking settings without going through the risky process of changing memory frequencies and voltages. If the XMP mode or DOCP profile (based on XMP) is enabled in the system’s BIOS, then that may cause the dev error 6661 as the overclocked settings of XMP may fail to properly execute the game. In this context, disabling the XMP or DOCP profile in the system’s BIOS may clear the dev error under discussion.

Warning:

Proceed at your own risk and with extreme care as editing a PC’s BIOS is a skillful task and if anything bad happens, you may brick your PC and cause undying damage to your PC or data.

13.1 Disable XMP in the System’s BIOS

  1. Boot your PC into its BIOS and steer to the M.I.T tab.
  2. Then expand Advanced CPU Settings and choose Extreme Memory Profile (X.M.P).
    Disable XMP in BIOS
  3. Now select Disabled and then save the changes made to the BIOS.
  4. Then exit the system’s BIOS and boot the PC into Windows.
  5. Now open Warzone and check if the game’s dev error 6661 is cleared.

13.2 Disable DOCP in the System’s BIOS

  1. Boot your PC into the BIOS and steer to its Advanced Mode.
  2. Now open AI Tweaker and set the dropdown of D.O.C.P to Disabled.
    Disable DOCP in the System’s BIOS
  3. Then save the changes and boot the system into Windows.
  4. Now launch Warzone and check if it is working normally without dev error 6661.

14. Update the System’s Bios to the Latest Build

If the system’s BIOS is outdated, then it may cause incompatibility between the OS and Bios, not letting the OS applications like Warzone access the resources essential for the game’s operation, thus causing the error 6661. Here, updating the system’s BIOS to the latest build may solve the problem.

  1. Update your PC’s BIOS as per the PC manufacturer:
  2. Once the BIOS is updated, check if Warzone is working fine.
  3. If not, check if performing an SFC scan of the PC resolves the Warzone issue.

15. Delete Files from the Data Folder of the Installation directory of the Warzone Game

You may also encounter the issue at hand if any of the latest update files (hosted in the Data folder of the installation directory) of the Warzone game are corrupt. In this case, deleting the files in the Data folder of the installation directory may solve the problem.

  1. Exit the Warzone game and close its launcher. Make sure to force close all the game-related processes in the PC’s Task Manager.
  2. Now right-click Windows and select Run.
  3. Then navigate to the installation directory of the Warzone game. Usually, the following (if you do not know the installation directory of the Warzone game, launch the Battle.net client, select Warzone, and open Show in Explorer):
    C:\Call of Duty Modern Warfare
  4. Now open the Data folder and again, double-click Data, so, the path will be as under:
    C:\Call of Duty Modern Warfare\Data\Data
  5. Now delete all the files with the .idx extension and all other files having the size of 1KB.
    Open the Data Folder of the COD Warfare Installation Directory
  6. Then, Scan and Repair the Warzone game (as discussed earlier), and afterward, check if the game is clear of the dev error 6661.
  7. If not, repeat the above steps except step 7, then delete all the files with the .idx extension.
  8. Afterward, delete the data.### files and files less than 10 MB in size (you can sort the files as per size).
  9. Then Scan and Repair the Warzone game in the Battle.net launcher to check if the issue is resolved.
  10. If that did not work, head to the installation directory of Warzone and delete the following files or files with the extensions below:
    .patch
    
    .result
    
    .product
    
    vivoxsdk_x64.dll
    
    Launcher.db
    
    Modern Warfare Launcher.exe
  11. Then Scan and Repair the Warzone game in the Battle.net launcher and afterward, check if the game’s dev error 6661 is cleared.

16. Reinstall the Warzone Game

If none of the above worked for you, then the installation of the game has become corrupt to a level where the launcher failed to repair it. In this context, reinstalling the Warzone game may solve the dev error under discussion.

  1. Firstly, make sure to back up the Warzone
  2. Then launch the Battle.net app and choose Warzone.
  3. Now click on its Settings icon and select Uninstall.
    Uninstall Call of Duty Warzone
  4. Then follow the prompts on the screen to uninstall Warzone.
  5. Once the Warzone game is uninstalled, restart your PC, and upon restart, right-click Windows and select Apps & Features.
  6. Now uninstall Warzone (if shown) and then restart your PC.
  7. Upon restart, navigate to the following paths (one by one) in the Run command box and delete the Warzone’s leftovers from these directories (where C is the system drive):
    %temp%
    
    %userprofile%\Documents
    
    C:\Windows\Temp
    
    C:\Program Files (x86)\
    
    C:\Program Files\
    
    C:\Program Files\Common Files\Blizzard Entertainment
    
    C:\Users\Public\Games\
    
    C:\Users\Public\Public Documents\Blizzard Entertainment\
  8. Afterward, restart your system and upon restart, reinstall Warzone (100 GB+ data).
  9. Once the Warzone is reinstalled, launch the game and hopefully, it will be clear of the dev error 6661.

17. Edit the Overclocking Settings of the System

Warzone is one of those rare games that is not comfortable with any type of overclocking and if any of your system components (like RAM) are in their overclocking condition, then that could be the root cause of the issue. Here, reverting the overclock settings of the system to the defaults or lower values may solve the problem. As it is not possible to cover all the possible scenarios, we will only list some general guidelines.

Warning:

Advance with utmost care and at your own risk as changing the overclocking settings of a PC is a skillful job and if not done properly, you may cause permanent damage to your system.

  1. Underclock your cores by -50 and RAM by -20.
  2. Now lower the voltage a bit and check if that resolves the issue.
  3. If not, check if increasing cores by +40 and MEM by +120, 114% solves the problem.
  4. If the issue persists, check if decreasing your cores by -15 clears the dev error.
  5. If that did not work, check if undervolting your GPU resolves the issue.
  6. If the error continues, check if setting the clocks to -15/1965 solves the problem.
  7. If not, check if reverting the overclocking settings to the defaults resolves the issue.

If the dev error is still occurring, then you may have to reinstall the system’s OS to clear the dev error 6661.

Kevin Arrows
Kevin is a dynamic and self-motivated information technology professional, with a Thorough knowledge of all facets pertaining to network infrastructure design, implementation and administration. Superior record of delivering simultaneous large-scale mission critical projects on time and under budget.
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