Black Ops 6 Dev Error 5820: Possible fixes, reasons, and more

The Black Ops 6 Dev Error 5820 appears whenever there is a network issue in the shooter. The very random yet frequent nature of this error ruins everyone's gameplay experience. You can simply be playing a match, loading into one, or maybe even finishing one, this error will pop up, kicking you out of the game lobby. Its appearance isn't just limited to these instances. It can even appear while you are you are just loading into the game from Call of Duty HQ, preventing you from even reaching the lobby screen.

Regardless of the cause, the error can be quite bothersome and ruin the game's experience.

It is a network-based error. Its appearance means that the client (your system) is unable to maintain a connection to the server. Now, the problem can be from both the server-side as well as client-side. If it is a server-side issue, there is little you can do as Call of Duty servers are beyond your influence. However, if it is the latter, then there are a few workarounds and fixes that you can definitely try.

That said, in this article, we'll be taking a closer look at some of the possible fixes for the Black Ops 6 Dev Error 5820.

How to possibly fix the Black Ops 6 Dev Error 5820

Before you get started with the Black Ops 6 Dev Error 5820 fixes, ensure that the game's servers are online. If they are not, then there's nothing you can do and you must wait till the servers are back up.

However, if they are up and you are still facing the error, you can try implementing the following fixes for Black Ops 6 Dev Error 5820:

Restart your router

Assuming you have already tried restarting your game, try restarting your router next. A proper reboot of your device will clear its cache and potentially resolve a host of network issues including the BO6 error. To reboot properly, disconnect all power cables from the device and let it remain idle for at least 30 seconds. Once 30 seconds have passed, plug the cables back in and boot it right back up. This should fix the Black Ops 6 Dev Error 5820.

Also read: Black Ops 6 Error 2901: Possible fixes and reasons

Allow the game through your firewall

Allowing Black Ops 6 through Windows Firewall to fix Black Ops 6 Dev Error 5820 (Image via Microsoft)

Sometimes, your firewall might prevent the game from connecting to the internet and cause the error. If you are using an anti-virus software, it probably already has its own firewall system. Check your anti-virus's firewall rules and ensure the game isn't blocked. If you're using Windows Defender, then Windows Firewall is the one protecting your system from threats online.

Follow these steps to allow the game through your Windows Firewall on Windows 10 and 11:

Launch the Control Panel.
Go to System and Security.
Select Windows Defender Firewall.
From the left panel, select Allow an app or feature through Windows Defender Firewall.
Now click on Change settings.
Look up Call of Duty core in the list and make sure the box next to it is ticked.
Restart your PC for the changes to take effect.

The Windows Firewall will now allow the BO6 client to connect to the internet and the Black Ops 6 Dev Error 5820 should be gone.

Use a different ISP

This is not the most ideal solution but it can help you diagnose the root cause of the problem. If you've got a second connection at home, use it to connect to the game and see if the error persists. You may also use your mobile hotspot. If you can now connect and play, then it becomes evident that the issue lies with your primary ISP and it is advised to contact them regarding the disconnects that are causing the Black Ops 6 Dev Error 5820.

Disable Teredo

Disabling Teredo in Windows 11 to resolve the Black Ops 6 Dev Error 5820 (Image via Microsoft)

If none of the abovementioned fixes worked and you are sure that your ISP isn't at fault, the next step to possibly fix the error is disabling Teredo. It is a protocol that essentially allows users with IPV4 internet to access IPV6 access. While that might not seem like a hindrance, it is known to cause issues with Call of Duty games and especially the newer titles such as Black Ops 6.

Here's how you can disable it:

Press 'Win+R' and type "cmd" (without the quotes) in the 'Run' box.
Press 'Ctril+Shift+Enter' to open the Command Prompt with Administrator rights.
Type “netsh interface teredo set state disabled” (without the quotes) in CMD and hit 'Enter'.
Now type “netsh interface teredo show state” (without the quotes) and check the status of the Teredo.

If you want to reverse the Teredo to its default values, follow these steps:

Type in "netsh interface teredo set state default" (without the quotes) in the CMD window.
Press 'Enter'.
Restart your PC.

That's it. After disabling Teredo, the Black Ops 6 Dev Error 5820 should be fixed and you should be able to play the game without any hiccups. However, if you're still facing the error, check out the final known fix in the section below.

Verify the integrity of game files

Verifying the integrity of Black Ops 6 files on Steam to fix Black Ops 6 Dev Error 5820 (Image via Valve)

With Black Ops 6, Call of Duty is making massive changes to its file system. With all the updates downloaded and the changes, some files might get corrupted. This can also prevent the game from connecting to the internet. Fortunately, all clients allow you to verify the integrity of game files and fix them if any broken or missing components are found.

Here's how to do it:

Steam

Navigate to your Steam game library.
Right-click on Call of Duty and select ‘Properties’.
Select ‘Installed Files’.
Click on ‘Verify integrity of game files’.

Battle.net

Launch Battle.net and head over to the Call of Duty tab.
Select the cog wheel next to the ‘Play’ button.
Click on ‘Scan and Repair’.
Finally, select ‘Begin Scan’ and click on 'Yes'.

Xbox App

Launch the Xbox App.
Select Call of Duty from the list of your installed games.
Right-click on it and select 'Manage'.
Click on the 'Files'.
Select 'Verify and Repair'.

Following the abovementioned steps will run a comprehensive check of the game files. If any file is missing or corrupted, the client will automatically download them. However, note that this can take a while based on your hardware, especially if you are using an old or slow HDD. This should potentially fix the Black Ops 6 Dev Error 5820.

Disclaimer: These fixes are not guaranteed to work.

That covers all the known possible fixes for Black Ops 6 Dev Error 5820. If you are still facing the error after implementing the abovementioned fixes, it's suggested to get in touch with the Activision technical support team for further assistance.

For more Call of Duty articles, check out the links below:

Edited by Sijo Samuel Paul