VAN 9101: Vanguard couldn't verify your PC (attestation failure)

VAN 9101: Attestation failure. This build of Vanguard cannot run on untrusted machines. Please restart your computer and try again.

What "untrusted machine" means here

The wording sounds like an accusation. Riot's article reads it more plainly: VAN 9101 is Vanguard failing to fully verify your system's current state, and it lists drivers, connected hardware and background programs as things that can interfere with those checks while the game is launching or already running. Nothing in the article connects it to a ban or a penalty.

Of all the Vanguard articles Riot has up, this is the only one that asks you to update drivers, and it puts that first. The restart lives in the error message alone (it isn't one of the numbered steps), so the article goes straight to drivers, then unplugging spare USB gear, then a clean boot, then making sure Windows is unmodified with every update installed.

Test each fix in Practice Tool

Because 9101 can fire mid-game as well as at launch, Riot suggests checking each fix in Practice Tool or a custom game where one's available. If the error comes back there, you haven't thrown a matchmade game or risked a penalty finding out. It's the same code in VALORANT, so the same advice holds there.

After all four steps, Riot's next stop is a ticket to Player Support with your logs attached.

Riot's fix, in Riot's order

1. 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

2. Unplug controllers and spare USB devices

   Unplug controllers, adapters and anything else on USB you don't need to play, restart, and launch again.

3. 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

4. Make sure Windows itself hasn't been modified

   Riot means an unmodified Windows install with the security features Vanguard needs switched on, and all updates installed. Debloated or customized Windows builds are the obvious suspects.

Related errors

• VAN 9100
• VAN -101
• VAN 0
• VAN: RESTRICTION

Source: Riot Games Player Support, Error VAN 9101, updated July 20, 2026. Riot's steps are paraphrased here, not copied; checked September 25, 2026.