Etherchannel and uplinks go down when second SFP is connected

[Merlin-Cisco]

Currently switches are connected via  SW1 Gig 1/0/25 > SW Gig 1/0/6

When I connect the second fibre link the channel goes down. Does the config look OK, what else could be causing this?

SW1

GB34SW1039#show run int gi1/0/25
Building configuration...

Current configuration : 210 bytes
!
interface GigabitEthernet1/0/25
description UPL*GB34SW1034*Gi1/0/6*Po16
switchport trunk native vlan 999
switchport mode trunk
switchport nonegotiate
channel-group 1 mode on
ip dhcp snooping trust
end

GB34SW1039#show run int gi1/0/26
Building configuration...

Current configuration : 210 bytes
!
interface GigabitEthernet1/0/26
description UPL*GB34SW1034*Gi2/0/6*Po16
switchport trunk native vlan 999
switchport mode trunk
switchport nonegotiate
channel-group 1 mode on
ip dhcp snooping trust

interface Port-channel1
description UPL*GB34SW1034*Po16
switchport trunk native vlan 999
switchport mode trunk
switchport nonegotiate
ip dhcp snooping trust
end

SW2

GB34SW1034#show run int gi1/0/6
Building configuration...

Current configuration : 287 bytes
!
interface GigabitEthernet1/0/6
description UPL*GB34SW1039*Gi1/0/25*Po1
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport mode trunk
switchport nonegotiate
spanning-tree bpduguard disable
spanning-tree guard root
channel-group 16 mode active
end

GB34SW1034#show run int gi2/0/6
Building configuration...

Current configuration : 287 bytes
!
interface GigabitEthernet2/0/6
description UPL*GB34SW1039*Gi1/0/26*Po1
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport mode trunk
switchport nonegotiate
spanning-tree bpduguard disable
spanning-tree guard root
channel-group 16 mode active

interface Port-channel16
description UPL*GB34SW1039*Po1
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport mode trunk
switchport nonegotiate
spanning-tree bpduguard disable
spanning-tree guard root
end

[mkazam001]

if you use mode active on channel group cmd - you're using LACP - so should use keyword passive on other side not on

sw 1 need to do - delete channel-group 1 mode on

use channel-group 1 mode passive

regards, mk

please rate if helpful or accept solution :)

[balaji.bandi]

SW1  should  be channel-group 1 mode passive/active If you want use LACP.

LACP mode active is to be preferred as it allows to exchange LACP control frames on each member link and allows to prevent some issues that can arise from errors in cabling

[Leo Laohoo]

What model of switch is this?
If this is a 3650/3850 then what IOS-XE version is this running on?