Customer observed core file generated in MX960 router after upgraded from Junos 19.4R3-S5 to 21.2R3-S7

RE0> show system core-dumps routing-engine both

re0: --------------------------------------------------------------------------

-rw-rw-rw- 1 root wheel 1387397120 Jul 10 10:57 /var/crash/vmcore.live.5

re1:

--------------------------------------------------------------------------

-rwxr-xr-x 1 root wheel 1326190592 Jul 10 11:00 /var/crash/vmcore.4*

lrwxr-xr-x 1 root wheel         8 Jul 10 11:00 /var/crash/vmcore.last@ -> vmcore.4

VMcore on the backup RE and at the same time, there has a live vmcore dump file being generated on the master RE.

After decoding the core dump files, the core dump on the backup RE1 is due to one of the NH failure to be allocated, it might be this NH had already been remove from the backup RE.

<2>panic: rnh_index_alloc: nhindex 3775 could not be allocated err=12

After the RE1 was rebooted, the problem could have been cleared. Customer can keep monitoring of the backup RE, this error won't affect the main service on the master RE0.