This article explains why CLI commands such as " show version ", " show system uptime ", and " show system core-dumps " result in the "error: error communicating with fpc0" error, and what must be done to resolve the error.

The show version , show system uptime , or show system core-dumps commands result in the following error:

root@switch# run show system uptime 
error: error communicating with fpc0

The related syslog message shows the following:

mgd[5102]: %DAEMON-3-UI_CHILD_SIGNALED: Child received signal: PID 5103, signal Broken pipe: 13, command='/usr/bin/uptime'

This problem may be observed when TACACS accounting is configured. In this scenario, every command (operational and configuration) is sent to the TACACS+ server for accounting.

The router has a five-second timeout for each TACACS+ server that is configured. If the TACACS+ server is not reachable within this time limit, the issue may be observed.

To resolve the issue, either remove the accounting configuration or if TACACS accounting is required, ensure that the TACACS+ server is reachable. For TACACS+ server configuration, refer to KB24265 - [EX/QFX] Configuration for TACACS Plus [juniper.net] . 

2020-01-30: Article updated to include a reference article for TACACS+ configuration; other minor changes made