Fix Error 51900101 in World of Warcraft

Some World of Warcraft (WoW) players are reporting a strange issue where the classic or cross-platform version of the game crashes with error code 51900101. When this error occurs, the game will disconnect you from the servers, preventing you from maintaining a stable connection.

If you want to know what you should do to fix this fault and what causes it, be sure to read this guide that we have prepared for you.

What causes error 51900101?

We have investigated a few reports from users who were dealing with this error and it is clear that there are several underlying scenarios that could be responsible for causing error 51900101. Here is a list of possible culprits that could be causing this problem:

• Continuous server errorIf you're experiencing this issue with every Classic or Burning Crusade server you try to connect to, it's likely that Blizzard is dealing with a server outage. This has happened multiple times in the past, and unfortunately, the problem is likely beyond your control. All you can do in this case is confirm the server issue and wait for the developers involved to fix the problem indefinitely.
• Incorrect DNS range: It turns out that this particular problem can also be caused by an incorrect DNS range that inhibits the connection between your PC and the WOW servers. In this case, you may be able to make the connection more stable by changing the IPV4 and IPV6 equivalents provided by Google.
• File corruption inside the cache folder: It turns out that another viable scenario that is confirmed to be causing this issue is some sort of corruption that is affecting the World of Warcraft file cache. To fix this issue, you will need to start by stopping all Blizzard-related services before deleting the main cache folder.

How can I fix error 51900101?

Now that we've gone over each of the possible causes of this error, let's review a number of methods that can help you troubleshoot the problem and identify the cause of it. Additionally, you'll be able to fix World of Warcraft error 51900101:

Check if there is an ongoing problem with the server

The first thing you should do if you experience error 51900101 with every realm in Word of Warcraft Classic and Word of Warcraft Burning Crusade Classic is to check if the underlying services are currently undergoing maintenance.

To perform this verification, open the World of Warcraft status page from your favorite browser.

Once you are on the status page, select the World of Warcraft Classic or Burning Crusade Classic tab (depending on which game mode is triggering error 51900101).

Next, scroll through the server list below and find the server causing the error. You can easily find it using the filters (top right corner) to filter the list by region and locale.

Once you've identified the server that's giving you trouble, check its status (left section of the screen). If the status has an exclamation mark, you've just confirmed that you're dealing with an underlying server issue that's out of your control.

Additionally, you can also check the official Twitter account @BlizzardCS for an official announcement regarding a server issue that the developers are trying to mitigate.

• If you have managed to identify the server issue, there is nothing you can do other than play on a different server (or realm) until the developers are successful in fixing the server issue.

On the other hand, if the investigation has not revealed any underlying server issues, continue with the next method below.

Change DNS to Google Equivalents

If you are experiencing this issue intermittently, you should also consider the fact that you might be dealing with an incorrect DNS (Domain Name System) range that is affecting the stability of your connection to the game server.

In case your ISP is using Tier 3 nodes, you may be able to alleviate the frequency of error 51900101 by switching to a DNS address range provided by Google.

Users confirmed that this method is effective, as we frequently receive this error after a few minutes of playing on a Classic or Burning Crusade Classic server.

Please follow the recommendations here for specific instructions on how to switch to a Google DNS:

• Open a Run dialog box by pressing key Windows + R. After this, you must write 'ncpa.cpl' and press the key Log in to open the window Network connections.
• Once you are inside the settings menu advanced network, go to the section on the right, scroll down to the section of related configuration and press click on More network adapter options.

• Once you are inside the menu Network connections specialized, right-click on the network you are currently using (Wi-Fi or Ethernet).

• After you are inside the dedicated menu of Ethernet o Wi-Fi, select the tab Networks in the menu at the top.
• In the next menu, move the cursor to the section This connection uses the following elements, then select Internet Protocol version 4 (TCP / IPv4) and click on the button Properties.

• When you get to the next menu, go to the General tab from the list of options, then check the box associated with Use the following DNS server address. 
• Once the custom DNS boxes are available, replace the current values ​​for the preferred DNS server and the alternate dns server with the following Google equivalents:

Preferred DNS server – 8.8.8.8

Alternate DNS Server – 8.8.4.4

• Then, when you manage to make the changes as specified above, click on Apply To save the changes.
• After the changes have been saved, return to the initial Properties screen and this time select Internet Protocol version 6 (TCP / IPv6) and click on the button Properties once again to modify the IPV6 DNS as well.
• After you get to the next screen, start by checking the box associated with Use the following DNS server address box and change the Preferred DNS Server and the Alternate DNS Server to the following values:

Preferred DNS Server – 2001:4860:4860::8844 Alternate DNS Server – 2001:4860:4860::8888

• To finish, you must click where it says Apply for the changes to be saved successfully. Once you do this, you will have replaced the default DNS range with the equivalent range from Google.

If the problem was indeed caused by a DNS issue , you should now be able to play World of Warcraft without experiencing the same 51900101 error.

In case this method does not fix the problem on your computer or if you were already using Google DNS, you can try the next solution.

Delete the cache folder

If changing the DNS address to the equivalent ones provided by Google does not work for you and you confirm that the problem is not caused by a server issue, the last thing you can do is delete the cache folder of your World of Warcraft installation.

It turns out that a corrupted cache folder can cause connectivity issues with World of Warcraft. This is even more likely if you're experiencing the same 51900101 error with every WoW server you try to connect to (even if the server status page shows no problems).

If this scenario is applicable, take note of these recommendations to delete the WOW cache folder:

Note: Deleting the World of Warcraft cache folder does not affect game data and should resolve most problems caused by corrupted temporary data and outdated files.

• First things first, make sure that World of Warcraft, Battle.net and all other Blizzard programs are closed and not running in the background.
• Next, you need to press the keys Ctrl + Shift + Esc to open the interface of the Task Manager.
• Once you're inside the Task Manager, Make sure you are viewing the interface of expertIf you can't see the different tabs, click on More details (bottom left section of the screen).

• When you are inside the advanced interface of the Administrator de homework, Click on the tab Processes on top.

• Next, scroll down through all the processes that are currently running and close them. agent.exe o Blizzard Update Agent by right-clicking and selecting End process.

• Once you have made sure that all Blizzard related processes are closed, close the task manager and then press the Windows key + R to open a dialog box Run. Inside the text box, type the command '%ProgramData%' and press Ctrl + Shift + Enter to open the folder Facts & figures of the SCHEDULE with administrator access.
• If inside the window User account control they ask you, you must click on Yes for administrator access to be granted.
• Inside the Program Data folder, locate the folder Blizzard Entertainment and delete it in a conventional way by right clicking on it and clicking on the icon/button Delete in the context menu.

• Launch the Battle.net desktop launcher once again and run World of Warcraft to see if the problem has already been solved.

I hope the information in this guide helps you solve this error once and for all. Thank you for always visiting us, see you next time. Until then.