Database Startup Fails With Errors ORA-01078 And ORA-27046 Or ORA-01078

Problem :
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Database startup fails with error

SQL> startup
ORA-01078: failure in processing system parameters
LRM-00109: could not open parameter file '......'

or,

SQL> startup
ORA-01078: failure in processing system parameters
ORA-01565: error in identifying file '.......'
ORA-27046: file size is not a multiple of logical block size
OSD-04012: file size mismatch (OS 2558)

Cause :
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The error can be happened in many scenarios.

1)The ORACLE_SID environmental variable is set improperly.

2)The error occurred as database could not find the spfile and pfile on the default location or specified location.(if startup pfile= is specified)

3)The spfile exists in default location but it is corrupted and hence reported ORA-01078.

4)If spfile exists in non-default location and we started by STARTUP pfile= where inside pfile it holds the location of spfile=location then error reported ORA-1078 along with ORA-27046. This scenario is explained in How to start your database with non-default spfile.

Solution -
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At first check whether your environment variable ORACLE_SID is set properly or not. On unix it is case sensitive. So dbase and Dbase is not same.

Is there is no way to repair or modify an spfile so try to solve the problem in following order.

1)If you have good backup of spfile then restore it. From RMAN you can easily do it if you have autobackup of controlfile. It is described in How to restore spfile by RMAN

2)You can get your pfile at the location $ORACLE_HOME/admin/$ORACLE_SID/pfile/. A typical file name is init.ora.418200821147. From that location first copy to another location like in /oradata2/pfile and then edit the pfile as necessary and try to make a spfile from that.
$SQL / as sysdba
$CREATE SPFILE FROM PFILE='/oradata2/pfile';

3)If the spfile backup does not exist then look at the database alert log file which is located in $ORACLE_HOME/admin/$ORACLE_SID/bdump. In the alert log file the list of non-default parameters listed. So create a pfile from spfile and later create spfile.

4)If you have corrupted spfile then from that, using binary utilities like strings available on unix open that and create pfile. And then create spfile from that. Like,

i)Follow either a or b part.

a)$strings /oracle/app/oracle/product/10.2.0/db_1/dbs/spfiledbase.ora >/export/home/pfile.ora

Now edit the /export/home/pfile.ora if any wrong character and then create spfile from that.
SQL>!vi /export/home/pfile.ora
SQL>create spfile from pfile='/export/home/pfile.ora';
SQL>startup

b)$strings /oracle/app/oracle/product/10.2.0/db_1/dbs/spfiledbase.ora
copy the usable contents inside it Open another file and paste contents into it.

SQL>!vi /export/home/oracle/test.txt

Create spfile from pfile.

SQL> create spfile from pfile='/export/home/oracle/test.txt';
File created.

Then start the database.