Error 21 occurs when the bike doesn't recognize the charger cable. When this happens, you can try to unplug and reinsert the charger cable. If that doesn't help, please try the steps below. 

Step 1: Firmware update

Make sure your bike has the latest firmware installed – you can check this on your app settings screen. If there is a new version available, install it. 

Step 2: Reset

Reset your bike: Press and hold the power button on the underside of the top tube for two seconds until you see the reset symbol on the Matrix Display. Press either handlebar button to power the bike on. If the bike is locked, use one of the 3 ways to unlock your bike.

Step 3: System restart

If a reset doesn’t help, you can also try a system restart in the app: 
- Make sure you’re connected to the bike and go to the VanMoof app > Garage > Help > System restart. During the system restart, a boat horn will sound and a boat will appear in the Matrix display. 
- After the restart, you can wake up your bike with a reset. 

Does the error still persist after these steps? 
Then it's best if your bike gets checked out by our Bike Doctors. Please book a repair appointment at your preferred VanMoof service location in the VanMoof app, or in your My VanMoof account.