After you changed your server the server type between suphp and DSO, you need to do the following solution for RVsitebuilder.
----------------------------------
For server administrator
----------------------------------
SSH to the server as root and run this command.

rm -rf /home/*/.rvsitebuilder/websitepublish/*/var/cache/tmpl
rm -rf /home/*/.rvsitebuilder/websitepublish/*/var/config
rm -rf /home/*/.rvsitebuilder/websitepublish/*/var/tmp
chmod 777 -R /home/*/.rvsitebuilder/websitepublish/*/var/cache

This will resolve the problem for all users.

---------------------
For End-users
---------------------
1.Access to your file system using FTP or File Manager.
2.Rename /.rvsitebuilder/websitepublish/{project_id}/var to /.rvsitebuilder/websitepublish/{project_id}/var.bak .
3.Create new var folder.
4.Change permission for var to 777.
5.Move the following folders in var.bak to the new var.
INSTALL_COMPLETE.php
{project_id}.conf.php
rvsautosetup.ini.php
rvstemplateconf.ini.php
subscribeMailList.txt
uploads

6.Change permission of moved files and folders on step5 and 6 to 777.
7.Republish the web site to restore entities and config folders on the new var. Make sure you check the checkbox for 'force update' in order to restore entities folder.