you can find it from:
http://www.cisco.com/en/US/docs/wireless/controller/message/guide/msgs6.html
Error Message %LWAPP-3-RX_ERR3: Received LWAPP packet with invalid sequence number
(got [dec]expected [dec]) - from AP [hex]:[hex]:[hex]:[hex]:[hex]:[hex]
Explanation LWAPP packet sequence mismatch has occurred, LWAPP packet was dropped. AP may not function as expected.
Recommended Action No action is required.