NERFPLZ.LOL
League of Legends error

Error 004: League couldn't finish patching

League clientPatching

The message

Patching failed and we're not sure why. Please restart the client to try patching again. (Error code 004)

What it means

A League update started and didn't finish. Riot ties it to the Riot Client lacking permissions, free disk space or network access while it patches.

What to try first

Exit the Riot Client from the system tray (closing the window isn't enough), reopen it and let the patch retry. Then check the install drive has room.

Is it you or Riot? If lots of players are hitting this at once, it's probably the servers. Check League server status before you start reinstalling things.

What 004 is telling you

Every League patch has two halves: the download, then the install over your existing files. Error 004 means one of those stopped partway, and the client quit when you clicked OK. Riot's dedicated article pins it on three things the Riot Client needs while it patches: permission to write the files, space on the drive, and a clear line to Riot's servers.

Riot's older error table says much the same thing in fewer words. It calls 004 either a connection problem or a disk that ran out of room, and that's why the storage check sits so high on the list below. If your drive is close to full, start there and skip the restarts.

It's a sibling of Error 002, which Riot describes as the same kind of patch failure.

Riot's fix, in Riot's order

Riot asks you to try the patch again after each step.

  1. Restart the Riot Client

    Close the game, then right-click the Riot Client icon in the system tray (bottom right, next to the clock) and pick Exit. Closing the window alone leaves it running. Open it again and launch.

  2. Restart your PC

    A full restart, not a sign-out. Vanguard's driver loads when Windows boots, so a restart is the only thing that gives it a clean start.

  3. Run the Riot Client as administrator

    Right-click the Riot Client shortcut and choose Run as administrator, then launch from there. If that fixes it, you can make it stick from the shortcut's Compatibility tab.

    Riot's guide: Run the Riot Client as administrator

  4. Free up space on the install drive

    Check the drive the game lives on. A patch needs room to download and unpack, and a nearly full drive fails partway through.

  5. Let the Riot Client through your firewall

    Add exceptions for the Riot Client and the game in Windows Defender Firewall and in any third-party firewall you run. Riot's firewall guide lists the exact files.

    Riot's guide: Let the Riot Client through your firewall

If it still won't patch

Riot's last two steps are heavier. First comes its full PC connection guide: wired instead of Wi-Fi, a router restart, a public DNS, and no VPN while you patch. After that, a clean reinstall of the game, which replaces any files the failed patch left broken.

One more thing worth checking if the patch hangs at 0% rather than failing outright. Riot has a separate article blaming that on antivirus clashing with a new patch, naming Avast and AVG, and suggests their Passive Mode just long enough to update (then switch it back off). If none of it works, send Riot a ticket with logs from its Riot Repair Tool attached.

What players found

Error 004 came in a wave. Players started reporting it around July 15, 2026, often on patches of only a few megabytes, and some who fixed it got it back on the next small patch. One player who filed a ticket found Riot's support site already listing it as a known issue.

What got people patching again, roughly in the order it came up:

  • Uninstalling Vanguard, reinstalling it and restarting by hand. Several players said this worked where repairing the game files as administrator didn't.
  • Deleting vgkbootstatus.dat from C:\Windows, removing the two Vanguard services from an admin Command Prompt, then restarting and launching again. A run of replies confirmed it.
  • Freeing space on the Windows drive itself, not only the drive League lives on. One player had a terabyte free on the game drive and still hit 004 until the system drive had room.
  • Resetting network settings in Windows, installing pending driver updates, or just restarting and opening the Riot Client as administrator.

A full wipe and reinstall of every Riot program also worked for some, though it was the most painful route and didn't always survive the next patch.

Player reports paraphrased from various Reddit threads, read September 25, 2026.

Other wordings of the same error

  • Error code 004
  • League error 004
  • Error 004 patching failed
  • LoL error code 004

Source: Riot Games Player Support, Error Code 004, updated July 15, 2026. Riot's steps are paraphrased here, not copied; checked September 25, 2026.