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Oracle problem: ora-12528: TNS: listener: all applicable routines cannot establish a new connection

Original description of the problem:

ORA-12528: TNS:listener: all appropriate instances are blocking new connections

Problems found:

By using lsnrctl status in CMD, we can find the following problems: blocked

Then: try to start Oracle Database:

[root@MyYun ~]# su - oracle
Last login: Thu Jul 18 22:01:58 CST 2019 on pts/1
[oracle@MyYun  ~]$ sqlplus/as sysdba
SQL> startup nomount;
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size		    2220200 bytes
Variable Size		  394268504 bytes
Database Buffers	  666894336 bytes
Redo Buffers		    5554176 bytes
SQL> select status from v$instance;

STATUS
------------
STARTED

SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

After executing the operation of the above code block, ora-12528 error occurs when using the third-party linking tool to link Oracle database locally

The solution is as follows:

Execute the following commands successively:

[oracle@MyYun~]$ sqlplus/as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Thu Jul 18 22:55:06 2019

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> shutdown;
ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux-x86_64 Error: 2: No such file or directory
SQL> startup
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size		    2220200 bytes
Variable Size		  394268504 bytes
Database Buffers	  666894336 bytes
Redo Buffers		    5554176 bytes
Database mounted.
exDatabase opened.
SQL> exit;
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

command explanation: & lt; br>

Shutdown command: equivalent to the following three commands

normal;
shutdown immediate;
shutdown abort;

Startup command: equal to the following three commands

startup nomount;
alter database mount;
alter database open;