Blocked Connection in listener
Blocked connection occurred when you listener is not registered with database, or when a database is in restricted mode and shutdown of the database is in progress.
If a database is in restricted mode, then LREG Backgroud process block all connections to the instance.
Clients are getting one of the following errors:
ORA-12526: TNS:listener: all appropriate instances are in restricted mode
ORA-12527: TNS:listener: all appropriate instances are in restricted mode or blocking new connections
ORA-12528: TNS:listener: all appropriate instances are blocking new connections
The ORA-12528 error occurs when a database instance is not yet registered with the listener.
Solution 1
1. If the database service registration is not listed, then enter the following SQL command:
--1. Check the service is registered with listener if not follow the next step.
lsnrclt services
--2. Connect with the database
sqlplus sys as sysdba
--3. Fire following command to register the Listener with Database
SQL> ALTER SYSTEM REGISTER;
You can set the listener parameter for register the Server:
-- Mention listener name
ALTER SYSTEM SET LOCAL_LISTENER=listener_sales1;
--In RAC you can also set remote listener
ALTER SYSTEM SET REMOTE_LISTENER=listener_sales2;
cmctl: is used for register the listener on linux or unix system.
CMCTL> ADMINISTER [instance_name]
Solution 2
Check database is not present in mount, nomount & restricted state if not then start the database in open state:
Startup
