How to Fix | ORA-01034: ORACLE Not Available error

Error

ORA-01034: ORACLE not available Process ID: 0 Session ID: 0 Serial number: 0

Vast majority of errors in Oracle can be divided into two categories. The first of which are errors caused by syntax issues, often small user-generated mistakes in typing or issuing commands. The second types are errors in the network, typically revolving around connectivity issues or memory space management. The ORA-01034 falls into this latter category as a primarily storage-based error.

Causes

An ORA-01034 error is triggered due to the Oracle system not being available or started up. This could derive from the System Global Area (SGA) necessitating more storage space than what is currently being allocated for your Oracle database. It could also be that operating system variable pointing to the instance was not properly defined. The error could also result during an upgrade of your Oracle systems.

Solutions

The ORA-01034 is almost always accompanied with additional error messages, often times ORA-27101: shared memory realm. ORA-01034 error could derive from the database parameters of your SGA being modified and no longer holding a proper amount of storage. You can go back and reissue the original parameters to potentially resolve this issue.

You should also check to make sure ORACLE_HOME and ORACLE_SID properly match. ORACLE_SID is the instance pointer mentioned before. Be sure that ORACLE_HOME is not followed by a trailing slash at the end. Search for ORACLE_SID using ‘echo $ORACLE_SID’ for Unix and by right-clicking the My Computer tab in Windows, clicking on Properties, then the Advance tab, and finally the Environment variable. You may find that ORACLE_SID is undefined or left blank, which is causing your ORA-01034 error.

If you believe the problem is the result of upgrading Oracle, you can check two files (/etc/oratab and /var/opt/oracle/oratab) for an invalid entry. Match the ORACLE_HOME and ORACLE_SID in these files. If they do not match, this needs to be resolved in order to resolve the error.

Actions

Refer to accompanying messages for possible causes and correct the problem mentioned in the other messages. If Oracle has been initialized, then on some operating systems, verify that Oracle was linked correctly. See the platform specific Oracle documentation.

The ORA-01034 error can sometimes be fixed by setting the ORACLE_SID environment variable:

Unix/Linux :

$ORACLE_SID=xxx 
$export ORACLE_SID
$sqlplus sys/manager@xxx as sysdba
SQL> startup

Window :

C:\> set ORACLE_SID=xxx
C:\> sqlplus sys/manager@xxx as sysdba
C:\> startup You may find that you are experiencing ORA-01034 when attempting to upgrade your Oracle database. 

ORA-01034 is thrown during the attempt to upgrade because there is an invalid entry in one of the following files:

1. /etc/oratab
2. /var/opt/oracle/oratab

The ORA-01034 is a result of a discrepancy between ORACLE_HOME and ORACLE_SID

To resolve ORA-01034, be sure that the ORACLE_HOME and ORACLE_SID properly match within the files /etc/oratab or /var/opt/oracle/oratab .

As a last step in solving your ORA-01034 problem and running DBUA, make sure that ORACLE_HOME is set to ‘old’ home, not ‘new’ home.

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