Symptom

On a Catalyst 9400 some ports could go into an err-disabled state due to BPDU guard as a result of packets erroneously looping between supervisor and line card. A shut/no shut of the interface will not recover these ports.

Conditions

9400 switch interfaces in err-disabled due to bpduguard when devices that are attached to these interfaces do not send out BPDU packets

Workaround

Reseat the affected line card.

Further Problem Description