"Failed to launch: something unusual happened": the Riot Client is being blocked

Something unusual has happened while trying to launch VALORANT. Try closing and restarting. If the problem persists, contact our player support team.

Why the message on Riot's page says VALORANT

Riot's article quotes the VALORANT wording, but it sits in Riot's all-games support section and talks about "a Riot game" throughout, so the same steps apply when League is the one that won't open. It also covers a plain "Failed to launch" error when a Riot game won't start or won't update.

Riot's general article on launch errors sends this message here too, so this is the list Riot wants you on.

Start with DevOverrideEnable

DevOverrideEnable is a Windows registry setting, and Riot says it can interfere with the system integrity checks the Riot Client relies on, which stops games installing, updating or launching. Turning it off happens in Registry Editor, and Riot has a dedicated guide for it. Follow that exactly (it's the registry, so change only the value it names), then restart.

Riot's fix, in Riot's order

If the registry change didn't do it, these are Riot's remaining steps, in its order. Try launching after each one.

1. Do a clean boot

   This switches off every non-Microsoft service for one boot, so you can tell whether something in the background is the problem.

   1. Press Win+R, type msconfig and press Enter.
   2. On the Services tab, tick Hide all Microsoft services first (skip it and you'll switch off parts of Windows).
   3. Click Disable all, then tick vgc again so Vanguard still starts.
   4. Apply, OK, restart, and test.

   Some programs ignore a clean boot anyway, third-party antivirus and networking tools most of all. If the error goes away, turn services back on a few at a time until it returns, and you've found it.

   Riot's guide: Do a clean boot

2. 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

3. Update every driver, not just graphics

   Update graphics, chipset and storage drivers from your PC or motherboard maker's own support page or tool rather than a driver-updater app.

   Riot's guide: Update every driver, not just graphics

4. Reinstall the game

   Uninstall from Windows' Installed apps list with the Riot Client closed. For a clean reinstall of League, Riot also has you delete the Riot Client folder under C:\Riot Games, the Riot Games folders under %localappdata% and %programdata%, and the League of Legends folder in Documents. That last one holds your replays, so copy them out first if you want them.

   Riot's guide: Reinstall the game

5. Uninstall Vanguard, restart, and let the game reinstall it

   1. Close the game and exit the Riot Client from the system tray.
   2. Right-click the red Vanguard icon in the tray, choose Advanced, then Uninstall Vanguard. If the icon isn't there, search Windows for Add or remove programs and uninstall Riot Vanguard from the list.
   3. Restart the PC. Vanguard is gone if its tray icon doesn't come back.
   4. Open the Riot Client and launch the game. It reinstalls Vanguard and will ask for one more restart before Play unlocks.

   Riot's guide: Uninstall Vanguard, restart, and let the game reinstall it

Still getting the box? Riot asks for a ticket with your logs attached.

Related errors

• Critical error
• System restart required
• Windows cannot access
• Unsupported operating system

Source: Riot Games Player Support, Error "Failed to Launch: Something unusual happened...", updated May 14, 2026. Riot's steps are paraphrased here, not copied; checked September 25, 2026.