HDP stack versions missing after upgrade to Ambari 2.4.2.0

OBSERVATIONS: After navigating to the "Register Version' we see that HDP 2.4 and 2.5 are not registered versions.

We identified some INFO level messages in the logs that tell us there is an issue with one of the xml files read by Ambari during startup;

15 Feb 2017 10:52:15,526 INFO [ambari-client-thread-67] AmbariMetaInfo:1417 - Stack HDP-2.0.6.GlusterFS is not active, skipping VDF
15 Feb 2017 10:52:15,528 INFO [ambari-client-thread-67] AmbariMetaInfo:1415 - Stack HDP-2.5 is not valid, skipping VDF: Could not parse XML /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE/configuration/arcadia-config.xml: javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE/configuration/arcadia-config.xml; lineNumber: 1; columnNumber: 1; Premature end of file.]; Could not parse XML /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.bak/configuration/arcadia-config.xml: javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.bak/configuration/arcadia-config.xml; lineNumber: 1; columnNumber: 1; Premature end of file.]; Could not parse XML /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.final.bak/configuration/arcadia-config.xml: javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.final.bak/configuration/arcadia-config.xml; lineNumber: 1; columnNumber: 1; Premature end of file.]
15 Feb 2017 10:52:15,528 INFO [ambari-client-thread-67] AmbariMetaInfo:1417 - Stack HDP-2.0.6 is not active, skipping VDF
15 Feb 2017 10:52:15,528 INFO [ambari-client-thread-67] AmbariMetaInfo:1417 - Stack HDP-2.3.ECS is not active, skipping VDF
15 Feb 2017 10:52:15,529 INFO [ambari-client-thread-67] AmbariMetaInfo:1415 - Stack HDP-2.4 is not valid, skipping VDF: Could not parse XML /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE/configuration/arcadia-config.xml: javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE/configuration/arcadia-config.xml; lineNumber: 1; columnNumber: 1; Premature end of file.]; Could not parse XML /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.bak/configuration/arcadia-config.xml: javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.bak/configuration/arcadia-config.xml; lineNumber: 1; columnNumber: 1; Premature end of file.]; Could not parse XML /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.final.bak/configuration/arcadia-config.xml: javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException; systemId: file:/var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE.final.bak/configuration/arcadia-config.xml; lineNumber: 1; columnNumber: 1; Premature end of file.]

In this case the file /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE/configuration/arcadia-config.xml was an empty. This generated an error that Ambari could not recover from and resulted in a failure to register the HDP stack version. As a result we could not add repositories for HDP 2.4 or 2.5. WORKAROUND: There are two ways to work around this issue. 1. Put at least one construct in the xml file indicated in the log file. For example;

<?xml version="1.0"?>
<!-- Some comment ->

This will prevent Ambari from throwing and exception and failing to register the HDP version. You will need to restart Ambari server after you update this file. 2. You can move the empty xml file to another directory and comment the entry out of the metainfo.xml file for the custom service. In this case we moved arcadia-config to /var/tmp. Modified /var/lib/ambari-server/resources/stacks/HDP/2.4/services/ARCADIA-ENTERPRISE/metainfo.xml and commented out the configuration file arcadia-config.xml. You will need to restart Ambari after making this change. SOLUTION:

This issue will be corrected in Ambari 3.0.0 via BUG-75022