1. Error Authenticating With Venmo? You will find the error authenticating with Venmo if Venmo knows you failing to fulfill its terms of use. If you take out any activity which is beside the usage policy of Venmo, then you will not be acceptable to access any of its services nor will you be allowed to sign in to your account. Therefore, if you need to make the greatest use of Venmo services, you shall try to take by its terms so that you do not look any issues while using it. error authenticating with Venmo