Avamar : Login to the VDP Configure page hangs due to a corrupted or unreadable VDR service configuration file

less /usr/local/avamar/var/vdr/server_logs/vdr-configure.log
<...>
2017-08-01 07:35:14,598 INFO  [http-nio-8543-exec-1]-services.LoginService: Login service called with action: [login]
<...>
2017-08-01 07:35:14,895 INFO  [http-nio-8543-exec-1]-services.LoginService: Sucesssfully autheticated
2017-08-01 07:35:15,160 ERROR [http-nio-8543-exec-3]-services.ConfigurationService: Unable to read and marshal the config file.
javax.xml.bind.UnmarshalException - with linked exception:
[org.xml.sax.SAXParseException; Premature end of file.]
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(Unknown Source)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:523)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:220)
        at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:189)
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)

• The VDR configuration file is unreadable or corrupted.  In the example shown below the file was actually empty

ls -ltrh /usr/local/vdr/etc/
total 28K
-rw-r--r-- 1 root root  449 Oct 21  2015 vdp-options.properties
-rw-r--r-- 1 root root 2.4K Mar 10  2016 vdr-configuration-deployed.xml
-rwxr-xr-x 1 root root  154 Mar 10  2016 vdrserver.cfg
-rw-r--r-- 1 root root 2.3K Apr  4  2016 benchmark-settings.xml
-rw-r--r-- 1 root root 1.6K Apr  4  2016 vdp_version_info
-rw-r--r-- 1 root root 2.8K Oct  7  2016 benchmark-result.xml
-rwxr-xr-x 1 root root  523 Jan  2  2017 vcenterinfo.cfg
-rw-r--r-- 1 root root    0 Jul 26 11:58 vdr-configuration.xml

The VDR server configuration file is corrupted or unreadable causing the login to the VDP configuration page to fail

1. Log in to the VDP appliance via an SSH session

2. Switch to the root user:  su -

3. Copy the content of the base configuration file vdr-configuration-deployed.xml to vdr-configuration.xml with the following command cp /usr/local/vdr/etc/vdr-configuration-deployed.xml  /usr/local/vdr/etc/vdr-configuration.xml

4. Reboot the VDP appliance