It looks like you are running out of memory while the content of the .sql file is being processed.
Use phpMyAdmin to find out what tables ,the ones that are being backupped, contain the most data. Also determin whether that data should be part of the backup or not.
Then in the Settings tab goto the “Database Backups” section and use the “Exclude Tables” setting to exclude large tables (data wise) from the backup. Make sure the following 3 iTSec tables are always excluded:
[prefix]itsec_temp
[prefix]itsec_lockouts
[prefix]itsec_log
Where [prefix] should be substituted by your WP table prefix.
Also make sure the “Backup Full Database” checkbox is disabled.
And last but not least make sure the “Schedule Database Backups” is disabled.
All of the above assumes that you are trying to create a single manual backup (“Create Database Backup” button) from the Backups tab\Menu option or (“Make a backup” button) from the “Important First Steps” popup window.
If the above info helps you resolve the issue please mark this topic as ‘resolved’.
dwinden
