This is the catch-all counter for packets received from this accounting server that were dropped for a reason not covered by the more specific malformed, bad-authenticator, or unknown-type counters. A rising value here without corresponding increases in the more specific error counters should send an admin to the device's system log for the actual drop reason, since this counter by itself only confirms that something was discarded, not why. For example, an accounting response arriving after its corresponding request has already timed out and been purged from the pending queue would typically land in this counter rather than a more specific one.