As it turns out, this particular issue has a wide array of potential culprits that might be ultimately responsible. To make things easier for you, we made a list of scenarios that are most likely contributing to the World of Warcraft problem you’re currently dealing with:
1. Check for an ongoing server issue
When you start troubleshooting this particular issue, you should start by ensuring that the issue is not beyond your control. It’s not uncommon for users to experience the BLZBNTAGT00000840 while the game client is in the middle of scheduled maintenance or when Blizzard engineers are busy patching a server issue in your region. Because of this, it’s important to take the time and investigate if other users in your area are currently experiencing issues with Battle.net and World of Warcraft. You can do so by checking the DownDetector listings of the two:
Word of Warcraft page on DownDetectorBattle.Net page on DownDetector
Note: If the investigation has revealed that other users in your area are also experiencing this type of issue, chances are the issue is indeed beyond your control. To be certain, you can also check the official Twitter support page of Blizzard for an official announcement related to the outage or scheduled maintenance period. On the other hand, if this investigation didn’t allow you to conclude that you’re dealing with a server issue, move down to the next potential fix below.
2. Reboot your PC
If you used the method above to make sure that you’re not dealing with an underlying server issue affecting World of Warcraft, the next thing you should do is troubleshoot against a potential glitches service that should be running in the background to facilitate the download of the update files. The quickest way to ensure that no glitched service dependency is running in the background is to simply reboot your PC and initiate the download immediately after the next startup is complete. In case the same Something went wrong with the file (BLZBNTAGT00000840) is still occurring even after you rebooted your PC, move down to the next potential fix below.
3. Grant admin access to Battle.Net
Now that you ruled out a potential glitched service from the list of culprits, the next thing you should do is ensure that the main game launcher (Battle.Net) has the administrative privileges to replace existing game files with new equivalents – to do this, it needs admin access. By default, Battle.net will be granted admin rights as you are being prompted by the UAC (User Account Control) window when you open up the launcher. But this might not happen if you use more aggressive UAC settings on Windows 10 or Windows 11. You can ensure that admin access is granted to Battle.Net by right-clicking on the main executable and clicking on Run as Administrator from the context menu. Note: At the UAC (User Account Control), click Yes to grant admin access. Once Battle.net is open with admin access, attempt to install the World of Warcraft update once again and see if the operation is complete. If the update now completes successfully, you can ensure that Battle.Net will always open with admin access by modifying the default behavior of the shortcut that you use. Follow the instructions below to force admin access on the Battle.net shortcut: If the problem is still not fixed, move down to the next potential fix below.
4. Disable or Uninstall 3rd party Security Programs (if applicable)
As it turns out, another potential cause that might actually cause this problem is an overprotective antivirus suite that is blocking the data transfer between the WOW download agent and the Blizzard server due to a false positive. Several users that were also dealing with this problem have confirmed that the problem was finally resolved after they either disabled or uninstalled the interfering 3rd party suite. Note: This method is only applicable for games using 3rd party suites – if you use Windows Security as your default antivirus, skip this method altogether. If you use an ordinary antivirus suite without a firewall component, it should be enough to disable the real-time protection. Note: You can typically do this by accessing the tray bar icon of your antivirus. However, if you’re using a 3rd party AV that includes a firewall component, the only viable action that fixes the issue is to uninstall the suite temporarily. This is necessary because the same security rules will remain in place even after you disable the real-time protection. Follow the instructions below to uninstall a 3rd party AV suite that includes a firewall component: If the same kind of issue is still occurring, move down to the next potential fix below.
5. Disable or Uninstall Add-on Managers (if applicable)
Keep in mind that the community around World of Warcraft has developed a lot of different Addon managers that make it easier to install community-created mods on the vanilla versions of WOW. However, it’s important to understand that the majority of these add-on managers will actually prevent the main Blizzard agent from installing the latest available updates available for World of Warcraft. So if you are looking to play the game as the original developers intended (on official servers and with the latest updates installed), chances are you’ll only be able to do so after disabling or uninstalling the add-on manager that you currently have installed. In some cases, you might be able to allow the update to go through without the BLZBNTAGT00000840 error simply by ensuring that the main process behind the WOW addon manager is closed and not running in the background. You can do this by opening Task Manager (Ctrl + Shift + Enter) and ending the process related to the addon manager from the Processes tab. If this doesn’t work and the same issues persist, the remaining option is to temporarily uninstall your add-on manager. Here’s how to do this: In case your attempts at updating World of Warcraft end with the same “Something went wrong with the file (BLZBNTAGT00000840)” error, move down to the next potential fix.
6. Run the repair tool
If none of the methods above have proven to be effective in your case, the next thing you should investigate is a potential issue brought about by some corrupted game files or game dependencies. This is especially likely if you have previously attempted to modify or replace certain game files belonging to World of Warcraft. You can expect to see the BLZBNTAGT00000840 in case the Battle.net update agent detects that the game installation folder contains file corruption. In this case, the solution is simple – you’ll need to repair the current World of Warcraft installation using the scan & repair functionality available inside Battle.net. Follow the instructions below for specific instructions on how to do this: In case the same problem is still occurring, move down to the next potential fix below.
7. Disable Proxy or VPN connections
Keep in mind that the update agent that Blizzard uses for their Battle.net launcher is notoriously known for being extremely picky when it comes to allowing updates to come through a connection funneled through a VPN or Proxy network. So if you are currently using a proxy or VPN connection, you would likely be forced to temporarily disable them (or even uninstall them) in order to be able to install the pending update. Depending on the technology that you’re using, you’ll either need to disable the anonymity solution or uninstall it from your PC. To help you with both potential scenarios, we’ve put together two separate guides that will guide you through this:
Disable the proxy server
If you’re on Windows 10 or Windows 11 and you’re using the native Proxy connectivity feature, this can be done directly from the Proxy tab of the Settings menu. Here’s what you need to do to disable the proxy server:
Disable or uninstall the VPN client
In case you are currently using a system-level VPN deployed directly using the native functionality (present on Windows 10 and Windows 11), you can revert the settings by visiting the VPN tab of the Settings menu. Here’s how: If this problem is still not fixed, move down to the next potential fix below.
8. Enabling the Secondary Logon service
A key dependency that is often overlooked by players engaging with Blizzard games is the Secondary Logon service. Note: Secondary Logon is a process that enables processes under alternate credentials. It’s heavily used by Battle.Net and every game released on the platform. This service should be enabled by default unless you modify its default behavior. If you’ve configured it to remain disabled, chances are that’s the reason why you are getting the BLZBNTAGT00000840 error while attempting to install the pending update. Follow the instructions below to ensure that the Secondary Logon service is enabled and properly configured via the Services screen: If the problem is still not resolved or this method was not applicable, move down to the next potential fix below.
9. Disable the World of Warcraft Voice Proxy in Task Manager
If you’re looking for a quick fix that a lot of affected World of Warcraft players have successfully used to get around this issue, you should also try disabling the WOW Voice Proxy service via Task Manager. Note: WowVoiceProxy has been the backbone for the voice chat functionality inside World of Warcraft since 2018. Although this service is completely harmless and should be kept enabled, increasingly more WOW players are blaming it for blocking new game updates carried over by the Blizzard update agent. Fortunately, there’s one workaround available in this case – opening Task Manager and force-closing the WOWVoiceProxy service before initiating the download inside Battle.net. Here are the complete step-by-step instructions on how to do this: If the attempt fails with the same BLZBNTAGT00000840 error, move down to the next potential fix below.
10. Delete CrashMailer from Overwatch folder
If you also have Overwatch installed on the PC that is currently exhibiting the BLZBNTAGT00000840 error, another scenario that you should investigate is a potential conflict with Overwatch’s 64-bit version of the Crashmailer (CrashMailer_64.exe) file. Note: CrashMailer_64.exe is a non-essential process that belongs to Overwatch. It’s a reporting tool that’s used to compile error logs when the game crashes unexpectedly. It’s in no way essential to the game and can be deleted – the Battle.net launcher will regenerate the file the next time you launch overwatch. Several affected users have discovered that by deleting the CrashMailer file, the conflict is temporarily resolved and the pending World of Warcraft update can finally be installed. Keep in mind that even if you end up deleting the CrashMailer_64.exe file, Battle.net will just regenerate it once again the next time you launch overwatch. So if you want to deploy this fix, follow the instructions below for specific instructions on how to do this: If the same kind of error is still occurring, move down to the next potential fix below.
11. Uninstall Riot Vanguard (if applicable)
If you’ve come this far without a viable solution, one last thing that you can try is to temporarily uninstall the Riot Vanguard installation. Note: Riot Vanguard is a custom anti-cheat system that’s designed to prevent gamers from cheating and upholding the latest industry-standard when it comes to competitive gaming. It’s primarily used for League of Legends and Valorant. If you have Valorant or League of Legends installed, there’s a very big chance you have Riot Vanguard installed too (since it’s bundled with both of these games). While this anti-cheat engine is great and we would encourage anyone to use it as intended, there are a lot of users blaming it for blocking certain updates coming through Battle.net (including pending WOW updates). Several users that we’re also dealing with this problem have confirmed that the WoW BLZBNTAGT00000840 error was finally resolved and the update went through after they temporarily uninstalled Riot Vanguard. Here’s how to uninstall Riot Vanguard from your PC (and reinstall it again):
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