League of Legends Error Code 004 has been experienced by many players after installing an update. It says that "Patching failed and we're not sure why. Please restart the client to try patching again. (Error Code 004)."
Error Code 004 usually involves something wrong with your permissions. Try right-clicking on the icon and "run as administrator" and if that doesn't help then make sure your Windows is updated and we'll go from there: ~GK
— Riot Games Support (@RiotSupport) June 16, 2018
League of Legends Error Code 004: How to fix
There are a number of reasons why error code 004 pops up. Typically, it is caused by the game lacking administrator privileges, which prevents patching, poor internet connection, a lack of space on the hard drive, or the copy of the game has been corrupted.
The first solution to try would be to run the game as an administrator. To do that, right click on the game icon, select "properties", click on the "compatibility" tag and check the box next to "Run this program as an administrator". Finally, press "apply" to save this change and restart the game again. Otherwise, check that your hard drive is not full, that you have strong internet connection, or temporarily turn off your anti-virus software to prevent it from messing up your download.
If these options do not work, download the Hextech Repair Tool from Hextech, the publisher of League of Legends. Follow their instructions and perform a "force repatch".
If you encountered the zero CS support bug, Riot has announced a fix for that too. Buffs for Zed are also in the works.
Photo courtesy of Riot
