Does your server still have both problems: credentials and rpmdb error?
Don't know if it will make any difference, but you could try to increase sssd timeout:
mkdir -p /etc/e-smith/templates-custom/etc/sssd/sssd.conf/
echo 'timeout=20' > /etc/e-smith/templates-custom/etc/sssd/sssd.conf/21domain_primary
The next time it fails check
journalctl -u sssd.service for any error before manually starting the service.
Check also the logs for any other error.