Symptom

Clients are not able to connect to the Wireless network after upgraded the 9800 WLC to 17.9.4a, unable to send M3, seeing a "CO_CLIENT_DELETE_REASON_KEY_M3_FAILURE" error log: [client-keymgmt] [15424] EAP key M1 Sent successfully [client-keymgmt] [15424] Client key-mgmt state transition: S_INITPMK -> S_PTK_START [client-keymgmt] M2 Status: EAP key M2 validation success [client-keymgmt] [15424]: (ERR): Keymgmt: Failed to prepare eap key m3 rsn key data. IGTK could not be included in M3 packet. [client-keymgmt] [15424]: (ERR): Keymgmt: Failed to process send key m3 failure. Send for M3 failed, lets delete the client

Conditions

+ PSK or 802.1x + WLC running 17.9.4a + 9120AX && 2802 APs + Flexconnect Local switching

Workaround

+ After we disabled and enabled the affected SSID, all the clients were able to connect.

Further Problem Description