There was an error while Re-Starting Our Newly Configured Oracle R12.2.6 Application Instance after a Hard reboot. I was unable to start some of the Server Components like oacore, oafm and forms.   When I tried to start them Manually, There was No error and everything seems to be started Successfully, But I was unable to access the URL with Below Error.

” Error 404–Not Found From RFC 2068 Hypertext Transfer Protocol — HTTP/1.1: 10.4.5 404 Not Found The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent. If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address. ”

This  is due to the failure of  oafm_server,Forms_server and oacore_server using EBS Startup scripts .Starting Using Web Logic Server Deployments as  below endup with Java Null Pointer Issues with state as”ADMIN”

“<Server ‘forms_server1’ in cluster ‘forms_cluster1′ is being brought up in administration state due to failed deployments.>

“(self-tuning)’> <<WLS Kernel>> <> <> <1417622780708> <BEA-149205> <Failed to initialize the application ‘oafm [Version=1.0.0]’ due to error java.lang.NullPointerException.
java.lang.NullPointerException
at java.io.File.<init>(File.java:251)
at oracle.apps.ad.util.AppStartupPropertyListener.preStart(AppStartupPropertyListener.java:89)
at weblogic.application.internal.flow.BaseLifecycleFlow$PreStartAction.run(BaseLifecycleFlow.java:290) ”

This is Due to the recent Change in Hosts file. My Database Lister Started with an Alias Name defined in the Host file and these Server Components were unable to start/connect to the Actual Host Defined.   Changing the Host Entry and restart of these Components  resolved the issue.

For More info Refer Below Oracle Metalink Document