How to Fix Error Code 900 in League of Legends

The causes for Error code 900 are, pretty much, the same as for most of the other Errors found in the League of Legends Game Client. In essence, every error code causes a disconnect between your PC and the League of Legends Client for a moment of time, which is enough for it to glitch out. 

As such, the solutions are generic as well for Error 900. How to fix League of Legends errors is only a matter of following the footsteps until one works out.

How to Fix Error Code 900 in League of Legends

Resetting the LoL Client

League of Legends is getting patched all the time, and yet the one thing Riot Games don't seem to plan on fixing is the League of Legends Client. So, the first solution of Error Code 900 can be found via the task manager. All you have to do is redo the process of booting itself:

1. Press ALT+F4
2. Sign Out
3. Press Ctrl+Shift+Esc to open Task Manager
4. Terminate all League of Legends processes
5. Open Riot Games Client
6. Sign Back In

Once that is done, the boot-up processes should be reset, and the issue should have gone away. That is, of course, if the cause was any of the processes there hindering you from playing League.

Restarting Your Router

The issue may also be caused by your internet connection. Thus we have a simple fix that most players should be able to think of by themselves, and that is restarting your router. We recommend doing so once a week, to make sure your router works optimally.

This is especially important for those that do not use ethernet cables to maintain an ethernet connection, and instead rely on WiFi, to maintain a stable internet connection.

Resetting Your Network Settings

If your router, that is hardware, is fine and the issue persists, then the issue may be found somewhere within your software. That would require you to:

1. Right-click the Start Button
2. Select Settings
3. Select Network & Internet
4. Click on Network Reset Under Advanced Settings
5. Reset Network settings
6. Restart your PC

By doing so you’ve reset your network settings, and if the League of Legends Error code 900 was caused by your internet connection to the Riot Games servers, this should solve the issue with connecting to said League of Legends servers.

Using the Hextech Repair Tool

The Hextech Repair Tool is a repair tool offered by Riot Games to help League of Legends players detect corrupt game files, which may cause issues such as high ping or FPS. It can also help to fix the Error Code 900.

The simplest way of using Hextech Repair tool is the default one, as it will cover all of your bases:

1. Launch Hextech Repair Tool
2. Select your region
3. Enable all options
4. Check the Firewall to give it a firewall exception
5. Click on the “Press Start” button
6. Restart your computer upon finishing

If this software cannot help you, it will forward you to the support team along with your information. It sends a ticket on your behalf including your system information, League logs, and other critical details.

Having this on your computer is very useful even if it doesn't solve the error you're currently experiencing.

Adding a Firewall Exception

Every once in a while, as the game is constantly getting new content with patches, the Windows firewall may stop the game or the Client from running properly.

That is why it is needed to enable firewall exception for the game in the firewall settings:

1. Open the Control Panel
2. Click on System and Security
3. Open Windows Defender Firewall Screen
4. Click on the Allow an App or Feature through Windows Defender Firewall
5. Find lol.launcher.exe and systemrads_user_kernel.exe and tick the boxes next to them
6. Click OK to save the changes

This is due to the fact that, every two weeks, League of Legends files change. And all it takes is for the firewall to find a single thing lacking, for the whole house of cards that is the League of Legends Client and its spaghetti code to break down.

Reinstalling League of Legends

To reinstall League of Legends is a relatively simple affair. However, when it comes to doing so to get rid of an error or a bug that is plaguing you, such as Error 900, you will need to remove all game files from your computer completely before you can continue to reinstall League of Legends, as these can be caused by corrupted files after all.

After all, should you fail to do so, the problem will persist as the Legends Client adapts to the files you already have installed:

1. Click on the search bar in the bottom left corner of your display,
2. Then, type in Apps & Features,
3. Open Apps & Features,
4. Search for League of Legends,
5. Select it, then choose to Uninstall League of Legends

Afterward, make sure to comb through your drives for Riot Games folders, and remove them indiscriminately, with all potentially corrupted game files. This is because, if you're down to this step, that means that even the Hextech Repair Tool was unable to differentiate which files cause this League of Legends Error Code, causing you to reinstall League of Legends as an act of desperation.

After that, it is simply a matter of reinstalling League of Legends from scratch. Unfortunately, as these are all general fixes for meant for any League of Legends Error Code, it is within the realm of possibility of it returning after a while, after which you will need to take the necessary steps once again.

Submitting a Support Ticket

The option of last resort is to contact Riot Games support. Much like in other online games, there’s a support team in Riot Games that should help you with everything regarding this matter or any other issues you may have.

So don’t hesitate to contact them, preferably with the data packet from the Hextech Repair tool in tow:

1. Visit the Official Riot games Website
2. Submit a ticket tech issue.
3. Upload the data packet from Hextech Repair tool
4. Wait for an answer from the support team.
5. Follow the offered solutions.

Riot Games have, until now, never given a direct solution to most of these bugs, errors and crashes the game and LoL Game Client experience. So, while tech support know their stuff, even they can get stumped sometimes so the option to contact Riot Games support may not be of much use.

One thing to note is that, much like the windows firewall, the League of Legends error code 900 can also be caused by a third-party security software. As such, it would be wise to root around your third part security software settings menu and make LoL an exception there as well.