Oracle WebLogic Server 10.3.6: weblogic.management.ManagementException

Error:
There are 1 nested errors:
weblogic.management.ManagementException: Unable to obtain lock on /export/home/oracle/mdw4/user_projects/domains/base_domain/servers/AdminServer/tmp/AdminServer.lok. Server may already be running at weblogic.management.internal.ServerLocks.getServerLock(ServerLocks.java:206)
at weblogic.management.internal.ServerLocks.getServerLock(ServerLocks.java:67)
at weblogic.management.internal.DomainDirectoryService.start(DomainDirectoryService.java:74)
at weblogic.t3.srvr.ServerServicesManager.startService(ServerServicesManager.java:461)
at weblogic.t3.srvr.ServerServicesManager.startInStandbyState(ServerServicesManager.java:166)
at weblogic.t3.srvr.T3Srvr.initializeStandby(T3Srvr.java:881)
at weblogic.t3.srvr.T3Srvr.startup(T3Srvr.java:568)
at weblogic.t3.srvr.T3Srvr.run(T3Srvr.java:469)
at weblogic.Server.main(Server.java:71)
> 
<Jan 2, 2014 4:20:35 PM CST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FAILED> 
<Jan 2, 2014 4:20:35 PM CST> <Error> <WebLogicServer> <BEA-000383> <A critical service failed. The server will shut itself down> 
<Jan 2, 2014 4:20:35 PM CST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FORCE_SHUTTING_DOWN> 

Solution:

1.Delete file:

/export/home/oracle/mdw4/user_projects/domains/base_domain/servers/AdminServer/tmp/AdminServer.lok, and re-start weblogic.

2.Restart test machine(reboot) and re-start weblogic.

http://unixadminschool.com/blog/manpages/solaris-file-etcnologin/

Error:
Caused By: javax.security.auth.login.FailedLoginException: [Security:090303]Authentication Failed: User weblogic weblogic.security.providers.authentication.LDAPAtnDelegateException: [Security:090295]caught unexpected exception

Solution:

1: remove the boot.properties file completely from the managed server directory.
2:remove ManagedServerDir(user_projects/domains/base_domain/servers/...)/data/ldap directory completely.
3: Always keep backup of files before removing it.
4: Now try to start the server from the command prompt and provide the username/password used to login to the Admin Console