As per PR 130067, when a peer device connected to S4810 running 9.2.x is rebooted or its interfaces is flapped, S4810 will send out the LACP PDUs with incorrect state that causes the LACP negotiation issue.
This PR on S4810 is fixed in 9.3 or later releases.
Below is the procedure to recover the port channel from the S4810 side, if the upgrade cannot be immediately performed.
4810#sho run int ten 0/31
interface TenGigabitEthernet 0/31
no ip address
mtu 12000
port-channel-protocol LACP
port-channel 128 mode active
no shutdown
4810#con
4810(conf)#in ten 0/31
4810(conf-if-te-0/31)#no port-channel-protocol lacp
4810(conf-if-te-0/31)#
4810(conf-if-te-0/31)#sho config
interface TenGigabitEthernet 0/31
no ip address
mtu 12000
no shutdown
4810(conf-if-te-0/31)#ex
4810(conf)#no int port-channel 128
4810(conf)#in ten 0/31
4810(conf-if-te-0/31)# port-channel-protocol LACP
4810(conf-if-te-0/31-lacp)# port-channel 128 mode active
4810conf-if-te-0/31-lacp)# no shutdown
4810(conf-if-te-0/31)#Oct 21 11:27:28 PST: %STKUNIT0-M:CP %IFMGR-5-ASTATE_UP: Changed interface Admin state to up: Po 128
Oct 21 11:27:31 PST: %STKUNIT0-M:CP %LACP-5-PORT-GROUPED: PortChannel-128-Grouped: Interface Te 0/31 joined port-channel 128.
Oct 21 11:27:31 PST: %STKUNIT0-M:CP %IFMGR-5-OSTATE_UP: Changed interface state to up: Po 128