# YubiKey troubleshooting

## When using a YubiKey with your Casa Vault, there are specific requirements and restrictions to ensure smooth functionality. This guide will help you troubleshoot common issues.

#### **YubiKey Firmware Requirements**

• **Firmware Version**: Ensure your YubiKey has firmware version **5.5 or higher**. If your firmware is outdated, you won't be able to use it as a Vault key. You'll need to get a new one.

#### **Browser and Device Compatibility**

• **Chrome Browser**: All signing actions with a YubiKey (e.g., adding a key to a vault, performing a health check, signing transactions) **must** be done using the **Chrome browser**.

• **Desktop Only**: These actions must be performed on the **Desktop version of Chrome**, not the mobile version. Attempting to use a mobile device will result in errors.

#### **Using YubiKey in your Vaults**

• **Multiple YubiKeys**: You **can** use multiple YubiKeys in a single vault. For example, you can have YubiKey A as your HOME key and YubiKey B as your OFFICE key.

• **Single YubiKey Roles**: You **cannot** use the same YubiKey for multiple roles within the same vault. For instance, YubiKey A cannot be both the HOME and OFFICE key in the same vault.

• **Multiple Vaults**: The same YubiKey can be used across multiple vaults. For example, YubiKey A can be a key in both a 3-key vault (3KV) and a 5-key vault (5KV).

#### **YubiKey for Passkey 2FA Login and Vault Key**

• **Distinct Uses**: A YubiKey **cannot** be used as both your passkey 2FA for login AND as a key in a vault. Casa intentionally blocks a YubiKey from being used for both authentication and signing for enhanced security.

#### **Troubleshooting Steps**

1. **If you get the "Check Firmware Version" screen**: Ensure your YubiKey firmware is 5.5 or higher. If your firmware version is below 5.5, you will need a new YubiKey.

2. **Use Chrome Browser**: Make sure you are using the Chrome browser on a desktop or laptop computer.

3. **Review YubiKey Assignments**: Verify that you are not trying to assign the same YubiKey to multiple roles in the same vault.

4. **Separate 2FA and Vault Keys**: Ensure you are not trying to use a YubiKey for both 2FA login and as a vault key.

5. **If shown a list of Passkeys, choose the email that belongs to the account**. If you previously had a vault key or keys on a YubiKey and then deleted one or more of them, it's possible when doing a health check or signing a transaction, a list of multiple passkeys will open. Select the passkey that displays the email for your account, then continue.

6. **Make sure "FIDO2" is toggled ON in your Yubico Authenticator app**. If it's turned off, set up will fail.

By following these guidelines, you can ensure that your YubiKey functions correctly with your Casa Vault. If you encounter any issues, double-check the steps above or contact support for further assistance.