wordpress 2.2.1 –> 2.6.3

I am attempting to do an upgrade from 2.2.1 to 2.6.3 via my hosting package (through CPanel and running automatic upgrade process).

The following error message is displayed:

Upgrading…

Initializing Parameters – Done.
Warning: system() has been disabled for security reasons in /tmp/cpanel_phpengine.1227518059.34446_2pyHIHir on line 1445

Upgrade failed

The database oncall_wrdp1 is not working properly and the creation of a database backup file has failed. Please contact the sysadmin for further assistance. Include this message for reference.

The initial installation has not been modified.

I emailed tech support at my hosting company and had the following reply

This is normally caused by a bad install of a script or a damaged database, you need to double check that
the authors of wordpress have not reported any problems with the upgrade on thier own support forum

Regards,

To date, there has been no errors or problems with the preconfigured installation and and I cannot find anything here on the support forum which would answer this problem.

Any advice people?

With thanks

Chris Hall