Symptom
N9K-C93180YC-FX running 9.3(10) with four fexes that keep getting disconnected, and sysmgr core files are generated. The fexes are third-party: N2K-B22DELL-P-FI and N2K-B22DELL-P.
%SYSMGR-FEX102-2-SERVICE_CRASHED: Service "System Manager (core-client)" (PID 7881) hasn't caught signal 15 (no core).
%SYSMGR-FEX102-2-SERVICE_CRASHED: Service "System Manager (core-client)" (PID 7983) hasn't caught signal 15 (no core).
%SYSMGR-FEX102-2-SERVICE_CRASHED: Service "System Manager (core-client)" (PID 8111) hasn't caught signal 15 (no core).
%SYSMGR-FEX102-2-SERVICE_CRASHED: Service "System Manager (core-client)" (PID 8239) hasn't caught signal 15 (no core).
%FEX-2-NOHMS_ENV_FEX_OFFLINE: FEX-102 Off-line (Serial Number FOC1914R1F2)
%ETH_PORT_CHANNEL-5-PORT_DOWN: port-channel7: Ethernet1/8 is down
%ETHPORT-5-IF_BANDWIDTH_CHANGE: Interface port-channel7,bandwidth changed to 10000000 Kbit
%ETHPORT-5-IF_DOWN_INITIALIZING: Interface Ethernet1/8 is down (Initializing)
%KERN-0-SYSTEM_MSG: [2989991.942906] unregister_netdevice: waiting for Eth102-1-15 to become free. Usage count = -14405 - kernel
%FEX-5-FEX_PORT_STATUS_NOTI: Uplink-ID 2 of Fex 102 that is connected with Ethernet1/8 changed its status from Disconnected to Configured
%KERN-0-SYSTEM_MSG: [2990043.134352] unregister_netdevice: waiting for Eth102-1-15 to become free. Usage count = -14405 - kernel
%KERN-0-SYSTEM_MSG: [2990053.255294] unregister_netdevice: waiting for Eth102-1-15 to become free. Usage count = -14405 - kernel
%KERN-0-SYSTEM_MSG: [2990063.496234] unregister_netdevice: waiting for Eth102-1-15 to become free. Usage count = -14405 - kernel
