Start without firmware changes. Use Riot Client repair for a non-VAN failure; for a stated security requirement, read Windows state and prepare backup and recovery access before model-specific guidance. Each article explains the next step if it still fails.
Sources
We checked these official pages and wrote the steps in our own words. Follow the publisher’s page if it has changed.
Riot: error VAN9003Riot: Secure Boot state and manufacturer resourcesMicrosoft: find your BitLocker recovery keyRiot: Vanguard security requirementsRiot: error VAN9001Riot: TPM readiness, specification and manufacturer guidanceRiot: Client Full Repair ToolRiot: game-launching errorsRiot: normal Vanguard uninstall and reinstallJapanese version of this page