If Oracle 11G reports that Enterprise Manager cannot connect to the database instance, You Can troubleshoot the problem as follows:
1. Use SQL PLUS.
Run SQL PLUS in DOS mode.
SQL> conn
Enter the User name: sys as sysdba
Enter the password:
Connection successful
SQL> desc dba_users Note: If this prompt shows that the view is invalid. Create user_astatus_map with D: \ oracle \ product \ 10.2.0 \ db_1 \ RDBMS \ ADMINsql. bsq. Otherwise, the following information is displayed:
Is the name empty? Type
-----------------------------------------------------------------------------
Username not null VARCHAR2 (30)
USER_ID NOT NULL NUMBER
PASSWORD VARCHAR2 (30)
ACCOUNT_STATUS not null VARCHAR2 (32)
LOCK_DATE DATE
EXPIRY_DATE DATE
DEFAULT_TABLESPACE not null VARCHAR2 (30)
TEMPORARY_TABLESPACE not null VARCHAR2 (30)
CREATED NOT NULL DATE
Profile not null VARCHAR2 (30)
INITIAL_RSRC_CONSUMER_GROUP VARCHAR2 (30)
EXTERNAL_NAME VARCHAR2 (4000)
SQL> select username, account_status from dba_users where username = 'sysmance ';
USERNAME ACCOUNT_STATUS
--------------------------------------------------------------
SYSMAN LOCKED
SQL> alter user sysman account unlock;
The user has changed.
Now the system can connect to the database.