Box art - Call of Duty: Modern Warfare

COD Modern Warfare & Warzone Dev error 6071 fix

Dev error 6071 is one of the least common problems faced by Call of Duty: Modern Warfare and Warzone players. However, it’s also one of the most persistent. Code 6071 seems to ignore almost all common solutions, and it won’t even let you get into the game to adjust other settings. However, there is one method you can use to fix dev error 6071 that is practically guaranteed to work. Here’s what you need to know.

Modern Warfare & Warzone | Dev error 6071 fix

How to fix dev error 6071 - Call of Duty Modern Warfare & Warzone

Dev error 6071 in Call of Duty: Modern Warfare and Warzone prevents the software from launching properly. You’ll hear the startup sounds, but the game will display black screen before crashing. Luckily, you can fix dev error 6071 by diving into the Windows 10 registry and changing your machine’s UUID.

Before attempting the registry fix, it’s worth trying some of the more common troubleshooting steps. Make sure Windows is up to date, and double check that you’re running the latest GPU drivers. Using the Scan and Repair tool in the Battle.net launcher is another a good idea that should rule out any problematic data. Finally, we recommend disabling any programs with in-game overlays — these seem to cause a lot of problems with Call of Duty software. With any luck, one of these will solve the problem.

However, if you’ve come here looking for a different fix, chances are those solutions haven’t worked. As it turns out, there’s a widely circulated fix for dev error 6071 that involves editing your PC’s UUID in the Windows Registry Editor. Here’s what you need to do.

How to fix dev error 6071

  1. Head to the UUID Generator website, generate a new UUID, and copy it to the clipboard (CTRL + C)
  2. Click the Start button and open Registry Editor
    • You can also press the Windows Key + R, then type regedit
  3. When the User Account Control dialog appears, click Yes
  4. In the left pane, navigate to HKEY_LOCAL_MACHINE > SOFTWARE > MICROSOFT > CRYPTOGRAPHY
  5. Double-click on the entry titled MachineGuid
  6. Enter the code you copied from the UUID Generator website
  7. Click OK, then close the Registry Editor

It is not immediately clear why this fix works. The MachineGUID registry entry is an identifying key unique to your PC. These are known as Universally Unique Identifiers (UUID), or alternatively Globally Unique Identifiers (GUID). Changing it somehow tricks the Call of Duty software into thinking it’s on a different computer — one that can run the game, apparently.

Dev error 6071 fix - Call of Duty Modern Warfare Warzone

With that said, there is some precedent to this fix. After Modern Warfare 2019 first came out, users who encountered dev error 6071 reported that only a fresh install of Windows would fix the problem. That’s a terrible solution for a lot of reasons, not the least of which is time wasted. However, reinstalling Windows just so happens to generate another UUID, which in turn fixes the problem. Strange, right?

Don’t use the same UUID code!

There are several versions of this fix where users recommend using a specific UUID, such as in this YouTube video or this Activision Support forum thread. However, using the same UUID string is not recommended for security purposes. It may work — and if everything else fails, you can try it — but we don’t consider fixes with security concerns to be proper solutions.

The risks outweigh the benefits: A common UUID can be used to find your MAC address or uncover other personal information. This is why it’s crucial to generate a unique code when using this fix.

After you’ve changed the MachineGuid registry key to a unique identifier, try to launch Modern Warfare or Warzone again. You should find that dev error 6071 has been miraculously fixed. This is a very weird solution for a rather uncommon problem, but it apparently works for the vast majority of users. If not, you’ll unfortunately have to get into contact with Activision Support.