In case you are not able to save your Braintree payment provider configuration, the descriptor may be set incorrectly.
The first part of the descriptor (before the asterisk) should be exactly 3, 7, or 12 characters long.
Periods are accepted, but not underscores or dashes. (In addition to alphanumeric characters)
So for example:
Onl*News
Online.*News
Online.Test*News