Error while starting WebLogic Server : java.lang.NumberFormatException: null

 I was working on WebLogic Server where Admin Server failed to start because Disk was 100% full. Admin Server failed to start after clearing some unwanted files from server with below error message

Error message in Admin Server log file $DOMAIN_HOME/servers/AdminServer/logs/AdminServer.log

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<aug 13, 2010 2:49:51 PM BST> <Critical> <WebLogicServer> <BEA-000386>
<Server subsystem failed. Reason: java.lang.NumberFormatException: null
java.lang.NumberFormatException: null
        at java.lang.Integer.parseInt(Integer.java:417)
        at java.lang.Integer.parseInt(Integer.java:499)
        at weblogic.ldap.EmbeddedLDAP.validateVDEDirectories(EmbeddedLDAP.java:1035)
        at weblogic.ldap.EmbeddedLDAP.start(EmbeddedLDAP.java:212)
        at weblogic.t3.srvr.SubsystemRequest.run(SubsystemRequest.java:64)
        Truncated. see log file for complete stacktrace
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Since error was point to embedded LDAP server for weblogic so I compared files related to embedded ldap server ($DOMAIN_HOME/ servers/ AdminServer/ data/ ldap/) with one of our running weblogic instance and found that size ofreplicas.prop file was 0 byte.

 $DOMAIN_HOME/servers/AdminServer/data/ldap/conf

-rw-r—– 1 oraowc dba 568 Aug 13 09:17 vde.prop
-rw-r—– 1 oraowc dba   0 Aug 13 09:17 mapping.cfg
-rw-r—– 1 oraowc dba   0 Aug 13 14:33 replicas.prop

.

Fix:

Option 1 - Open

 $DOMAIN_HOME/servers/AdminServer/data/ldap/conf/replicas.prop and add line
replica.num=0

or

Option 2- Move file $DOMAIN_HOME/servers/AdminServer/data/ldap/conf/replicas.prop to replicas.prop.bak  (On Restart WebLogic Server will recreate this file)