ORA-08102: index key not found

Below is the step to investigate the error and fix it.

o.s.s.s.TaskUtils$LoggingErrorHandler - Unexpected error occurred in scheduled task.

org.springframework.jdbc.UncategorizedSQLException: StatementCallback; uncategorized SQLException for SQL [update UNIDBA.UNITBS 

state [72000]; error code [8102]; ORA-08102: index key not found, obj# 78687, file 11, block 183997293 (2)

; nested exception is java.sql.SQLException: ORA-08102: index key not found, obj# 78687, file 11, block 183997293 (2)    

                Caused by: java.sql.SQLException: ORA-08102: index key not found, obj# 78687, file 11, block 183997293 (2)

Best way is :- Drop that index and recreate it.

 select substr(object_name,1,30), object_id ,object_type from dba_objects where  object_name='UNITBS';

SUBSTR(OBJECT_NAME,1,30)        OBJECT_ID OBJECT_TYPE

------------------------------ ---------- -------------------

UNITBS                     3845262   INDEX

ANALYZE INDEX index_name COMPUTE STATISTICS
ANALYZE INDEX index_name VALIDATE STRUCTURE