No puedo cambiar una web a Webempresa

Hola:
Tengo una web corriendo en Joomla 2.15.14 en Webfusion que quiero pasar a Webempresa pero no puedo porque Akeeba Backup me da el siguiente error:
Backup Failed
The backup operation has been halted because an error was detected.
The last error message was:

AJAX Loading Error
HTTP Status: 500 (Internal Server Error)
Internal status: error
XHR ReadyState: 4
Raw server response:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, hosting-support@webfusion.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Apache Server at turismotriacastela.com Port 80
Please click the 'View Log' button on the toolbar to view the Akeeba Backup log file for further information.

We strongly recommend going through the step-by-step instructions in our troubleshooting wizard to easily resolve this issue yourself. If this doesn't help, you may consider buying a FORUMACCESS subscription so that you can ask for support in our support forum. If you do post to our forum, please remember to ZIP and attach your backup log file in your post so that we can help you faster.

¿Cómo puedo hacer la copia o el cambio?.
Gracias