Notifications are received reporting cPhulkd being down, though the cause is not explicitly clear.
You may issue the following command to observe the failer, as reported by journalctl:
journalctl -u cphulkd --no-pager
Here, you may observe the following error:
cphulkd.service: main process exited, code=exited, status=255/n/a
While within the cPanel error log, you'll find corresponding errors reporting:
Cpanel::Exception::ProcessFailed::Error/(XID 7wzxvq) “/bin/rpm” reported error code “1” when it ended: error: rpmdb: BDB0113 Thread/process 31311/140435644479552 failed: BDB1507 Thread died in Berkeley DB library
This indicates that the RPM database is corrupted and needs to be addressed.
You may issue the following script, in order to rebuild the RPM database: