Messages Outbound Errors is the number of ICMP messages that were not send due to problems within ICMP, such as lack of buffers. ...

Messages Outbound Errors is the number of ICMP messages that were not send due to problems within ICMP, such as lack of buffers.  This value does not include errors discovered outside the ICMP layer, such as those recording the failure of IP to route the resultant datagram.  In some implementations, none of the error types are included in the value of this counter.