While installing or upgrading Red Hat Satellite 6, katello-installer fails with error "/usr/sbin/foreman-rake db:seed returned 1 instead of one of [0]"

Issue

• While installing Red Hat Satellite v 6, the installer fails with the error below:

# satellite-installer     # or katello-installer before 6.2
.
.
/Stage[main]/Foreman::Database/Foreman::Rake[db:seed]/Exec[foreman-rake-db:seed]: Failed to call refresh: /usr/sbin/foreman-rake db:seed returned 1 instead of one of [0]
 /Stage[main]/Foreman::Database/Foreman::Rake[db:seed]/Exec[foreman-rake-db:seed]: /usr/sbin/foreman-rake db:seed returned 1 instead of one of [0]
Installing             Done                                               [100%] [.....................................................................]
  Something went wrong! Check the log for ERROR-level output
  The full log is at /var/log/katello-installer/katello-installer.log

• During Satellite Server minor upgrade from v.6.2.8 to v.6.2.9, fails with below error :

[DEBUG 2017-05-10 15:04:54 main]  /Stage[main]/Certs::Candlepin/Exec[import client certificate into Candlepin keystore]/unless: keytool error: java.lang.Exception: Alias <katello-default-ca> does not exist
[ WARN 2017-05-10 15:05:13 main]  /Stage[main]/Foreman::Database/Foreman::Rake[db:seed]/Exec[foreman-rake-db:seed]/returns: Net::HTTPFatalError: 502 "Proxy Error ( Forefront TMG denied the specified Uniform Resource Locator (URL).  )"
[ERROR 2017-05-10 15:05:13 main]  /Stage[main]/Foreman::Database/Foreman::Rake[db:seed]/Exec[foreman-rake-db:seed]: Failed to call refresh: /usr/sbin/foreman-rake db:seed returned 1 instead of one of [0]
[ERROR 2017-05-10 15:05:13 main]  /Stage[main]/Foreman::Database/Foreman::Rake[db:seed]/Exec[foreman-rake-db:seed]: /usr/sbin/foreman-rake db:seed returned 1 instead of one of [0]
[ INFO 2017-05-10 15:05:13 main] /usr/lib/ruby/site_ruby/1.8/puppet/util/errors.rb:106:in `fail'
[ERROR 2017-05-10 15:05:35 main] Upgrade failed during the installation phase. Fix the error and re-run the upgrade.

• Satellite Installer for v.6.3.x fails at foreman-rake-db:seed step with below error:

[ INFO 2018-07-18 08:36:31 main]  /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Starting to evaluate the resource
[DEBUG 2018-07-18 08:36:31 main]  Foreman_smartproxy[satellite.example.com](provider=rest_v3): Making get request to https://satellite.example.com/api/v2/smart_proxies?search=name=%22satellite.example.com%22
:
:
[DEBUG 2018-07-18 08:36:31 main] The environment variable HTTP_PROXY is discouraged.  Use http_proxy.
:
:
[ERROR 2018-07-18 08:37:51 main]  /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Could not evaluate: Exception 500 "Internal Server Error" in get request to: https://satellite.example.com/api/v2/smart_proxies?search=name=%22satellite.example.com%22