Vanguard issues

Close Riot Client

Open Task Manager → Details, find RiotClientServices.exe, and end that process.

Remove the incomplete installation

Try removing the C:\Program Files\Riot Vanguard folder. If files remain in use, open Command Prompt as administrator and run these commands, one at a time:

sc stop vgc
sc stop vgk

Try deleting the Vanguard folder again if it is still there.

Reinstall Vanguard

1. Open Riot Client to start reinstalling Vanguard.
2. Close the loader while the installation runs.
3. Let Vanguard finish its normal installation.

Try the loader again

1. End RiotClientServices.exe in Task Manager once more.
2. Open the loader and select Uninstall Vanguard.
3. When that step finishes, open Riot Client again.

Open Riot Client with Run as administrator throughout these steps.

If the problem continues, contact support with the exact error and the last step that completed.