This morning, when running through our logfiles, looking for things gone wrong during the past 24H. We came across an error message repported by RMAN. A quick look at the message, and in the alert log, showed us this. 

Wed Dec  9 02:04:37 2009
Starting control autobackup
Autobackup failed with following error
ORA-19583: conversation terminated due to error
ORA-01565: error in identifying file /opt/oracle/10.2.0.4.0/dbs/spfileXO.ora
ORA-27046: file size is not a multiple of logical block size

However it only took some seconds, for a colleague to remember, editing the SPfile for that database, directly yesterday. However if you do that the SPfile become corrupt - so dont ;)

For us, we had a fresh pfile - so if was just a matter of getting a window to shutdown the database, erase the currupt SPfile, startup and create a new SPfile again.

SQL> create spfile from pfile;