Why am I receiving TEMPORARY_BAN_TOO_MANY_REQUESTS when attempting to Login?

You have made more than 100 successful login requests in a minute.  In the event of a breach of the login limit the account will be prevented from creating new login session for a 20 minute period. The error TEMPORARY_BAN_TOO_MANY_REQUESTS will be returned in these circumstances. All existing sessions will continue to be valid.