BLZ51901016 is one of the commonest error codes experienced by Blizzard gamers. If you are getting this error code, it means that you are having connection issues, or your PC does not meet the minimum system requirements for the game. There are several ways you can successfully resolve this problem, as discussed below. 

Solving Blizzard Error Code BLZ51901016

To solve the BLZ51901016 error code, you will need to check and reset any incorrect Host files, resolve network card issues, or upgrade your PC hardware. You may also need to disable any proxies that may be interesting with your login module. 

Before you try anything else, you should first check the  to see whether the service is online. If you are having a connection or login issues with World of Warcraft, you should check the page. If the service is offline, you should just give it some time and try later on. 

If the service is online, and you are experiencing high latency or frequent disconnects, try the following steps to troubleshoot and fix the problem: 


Step1: Reset the WoW User Interface 


If you are having interface and display issues, resetting your user interface to default can resolve the problem. First, you will need to temporarily uninstall any add-on management software you may have installed on your computer. 

This is done to prevent the add-on manager from re-syncing the data cleared in the following steps. Now exit the  World of Warcraft completely. In the Blizzard, desktop application click on “Options” and navigate to “Show in Explorer” (in Windows) or “Reveal in Finder”(in Mac OS). 

Now you should open the “World of Warcraft”, and open the folder for the game version you are using: classic or retail. In this folder, rename the interface, cache, and WTF folders to InterfaceOld, CacheOld, and WTFOld respectively. Re-launch the World of Warcraft for the changes to take effect. 


Step 2: IP Release, Renew, and Flush the DNS


If the problem persists after resetting the interface, you should try releasing, renewing, and flushing the DNS information that addresses networking issues. The procedure for doing this varies depending on the operating system you are using, as described below:

For Windows 10 and 8

From the desktop, press the Windows Key, and type CMD to reveal a command prompt. Right-click on the prompt, and select “Run as Administrator”. Now type ipconfig /release into the command prompt and allow the system some time to execute the command. 

Once you get a message that the IP address has been released, type ipconfig /renew into the command prompt. After a few seconds, you will get a message that the IP address has been re-established. Once again, type ipconfig /flushdns in the command prompt. 

Once you are done, close the command prompt and try establishing the connection once again. 

For Windows 7 

Click on the start button and select programs. Select accessories and navigate to the “Command Prompt Shortcut”. Right-click on this shortcut and select “Run as Administrator” from the drop-down menu that comes up. 

This will reveal a command prompt, type ipconfig /release into the prompt. Wait a bit for the IP address to be released before typing ipconfig /renew into the command prompt. You will get a message that the IP address has been re-established. 

Now type ipconfig /flushdns into the command prompt in order to flush the DNS. Close the prompt and check whether the error has cleared. 

For Mac OS 

The procedure for releasing, renewing, and flushing your DNS information on Mac computers is a bit different. If you are using a Mac computer, you need to open the Network Status Menu: From your Apple menu, navigate to System Preferences and select Network. 

Select the active connection from the “Network Status menu” that comes up and then click on Advanced. Select TCP/IP and then click Renew DHCP Lease. Allow the computer some time to complete the command, it will take just a few minutes. 

Once done, close the Network window and proceeds of flush the DNS cache. To do this, you need to open the Terminal: Go > Utilities > Terminal. Depending on the Mac OS version you have, you should enter the following command in order to flush the DNS:


For macOS High Sierra(10.13), macOS Sierra (10.12), and OS X El Capitan (10.11), enter: sudo dscacheutil -flushcache


For macOS Yosemite (10.10 through 10.10.3), enter: sudo discoveryutil mdnsflushcache
For macOS Yosemite (10.10.4+), enter: sudo killall -HUP mDNSResponder

Once you are done, close the command prompt and try re-establishing the connection. If you are not comfortable using the command prompt, restarting the computer may produce the same effects in all the above-mentioned operating systems. 


Step 3: Power Cycling the Network Devices 


Power cycling the router and modem will force them to reset and re-establish a connection to the Internet Service Provider (ISP). This will come in handy if the BLZ51901016 error to are getting is a result of a connection problem. 

If your modem has a backup battery, you should take it out or press the reset button to reset the modem. After that, you need to shut down all computers connected to the router/modem. Now proceeds to power the router down and unplug its power cord from the socket. 

Allow the router to sit unplugged for about 60 seconds. Plug the power cord back in and turn the router on. Allow them to boot up completely until the front panel signals that you are ready to connect. Now start the computer and try establishing a connection to see whether the error was resolved. 

Final Verdict 

The BLZ51901016errorncan occurs simply because the service is down. If you getting such an error, you should first check the BlizzardCS Twitter or the Realm Status page for World of Warcraft. If these reveal that everything is okay, then the problem lies with your hardware and software components. 

If you are experiencing high latency, frequent disconnect, or are unable to connect, the above-described steps will help you resolve the BLZ51901016 error. 


My name is Jim Kevin Taylor, also known as, Jimmy The Geek, I recently graduated from MIT with computer science major. I intern at a network security firm. I am passionate about solving technical issues.

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