Hey @wordpressdharma, thanks for coming back to us!
The Braintree Vault is a way for customers to store their credit card information against their user profile within your WooCommerce store.
For security reasons, we don’t want to actually store the raw card details in your database, so we use the libraries provided by Braintree to request the card to be stored in their Vault. Braintree then passes back a unique token for the customer that we can store, and then use for future payments. This process of storing the card and receiving back just a token is called tokenization – and a lot of other payment gateways support this feature too!
It does mean that customers can then use the card again without having to input their full card details. I’m not sure where your previous comment came from (was it from technical support?) or if this is what you are seeing on your store, but certainly, I wouldn’t expect customers to only be able to use their card once if it is Vaulted. That’s the opposite of the functionality of the Vault!
Unfortunately, the error message you’ve mentioned in your original post is a generic error message provided by WooCommerce when something goes wrong. This could be anything from incorrect credentials, to incorrect account configuration, or even a general decline from Braintree. We would need the log file that Pit mentioned previously to be able to look into this further for you.
Would it be possible to run through another test and provide us the file for further investigation?
Cheers!
Simon.