Stack wise port-channel error disable

[Ayub]

Hi, 

I face a problem today regarding channel-group mismatch. 

*Feb 25 13:23:40.107: %PM-4-ERR_DISABLE: channel-misconfig (STP) error detected on Po10, putting Gi1/0/1 in err-disable state
*Feb 25 13:23:40.111: %PM-4-ERR_DISABLE: channel-misconfig (STP) error detected on Po10, putting Gi2/0/1 in err-disable state
*Feb 25 13:23:40.119: %PM-4-ERR_DISABLE: channel-misconfig (STP) error detected on Po10, putting Po10 in err-disable state

I am having two 3850 12P in stack. When i tried to connect one link from each 3850 in port-channel with 2960x i got above erorr. 

My configuration is:

2960x

interface gig 1/0/49

 channel-group 1 mode on

 no shut

interface gig 1/0/50

 channel-group 1 mode on

 no shut

interface port-channel 1

 switchport mode trunk

 no shut

3850

interface gig 1/0/1

 channel group mode on 

 no shut

interface gig 2/0/1

 channel group mode on

 no shut

Interface port-channel 1

 switchport mode trunk

 no shut

The strange thing is port-channel comes-up for 10 to 15 sec and sundenly goes down with this message.... 

*Feb 25 13:23:40.107: %PM-4-ERR_DISABLE: channel-misconfig (STP) error detected on Po10, putting Gi1/0/1 in err-disable state
*Feb 25 13:23:40.111: %PM-4-ERR_DISABLE: channel-misconfig (STP) error detected on Po10, putting Gi2/0/1 in err-disable state
*Feb 25 13:23:40.119: %PM-4-ERR_DISABLE: channel-misconfig (STP) error detected on Po10, putting Po10 in err-disable state 

[Philip D'Ath]

Are they both using the same spanning tree mode (for example, rapid)?

[Ayub]

Yes Philip they are using the same.

[Georg Pauwen · Accepted solution]

Hello,

try:

channel-group 1 mode active

instead of 'mode on'. 

[Leo Laohoo]

Let me guess, the link on the 3850 is an SFP?
What is the firmware version running on the 3850?