In an attempt to backup an Oracle 10g Express Edition using their handy Backup scripts that are automatically put in your start menu, I ran into the following error:
====================ERROR============================= Backup of the database failed. Unknown log mode : SP2-0640:. Log file is at SP2-0640:. ====================ERROR=============================
In searching I found a post about changing the username password in the Batch file. This started me down the wrong road but he did make the sound suggestion of turning the echo on. There are about six places where the script stores log files in the %temp% directory and when I looked each one of these files read:
SP2-0640: Not connected
Turns out even when I tried to log on using two logins that I KNEW had administrator rights I could still not log in as a sysdba. The solution for a Windows user was to edit the Local Users and Groups and add the current user to the ORA_DBA group.
Side note: Another reason you might get this error is if your database is offline.