Symptom

Catalyst 9000 switches running 17.9.4a, in a stack, may reload unexpectedly with Last reload reason: Critical process fed fault on fp_0_0 (rc=139).

Conditions

This issue has been detected when configuring an IPSEC VTI tunnel interface to create a backup connection. - The LTE router gets a dynamic IP from the provider. This is not a Cisco router. The router is connected to each switch and spanning tree disables a port to have no loop. - There is no productive traffic through the LTE router. To test the VPN tunnel with a new IP, a reload of the LTE router is performed. The expected port down messages are detected and the configuration is saved. Afterwards, all switches in the stack crash.

Workaround

There are no known workarounds for this issue.

Further Problem Description