Problem

You access RVsitebuilder 6 from cPanel but see this error "ERR_TOO_MANY_REDIRECTS"
and redirect to url

/3rdparty/rvsitebuilder/ionctestlic-pro.php?redirect=

Solution
Please follow.
https://support.rvglobalsoft.com/hc/en-us/articles/360000124573-Run-install-update-RVsitebuilder-gives-Loop-Error-cgi-rvsitebuilder-setup-php-Request-

If not resolve, Please contact your host provider to run force update with command.

perl /usr/local/cpanel/whostmgr/docroot/cgi/rvsitebuilderinstaller/autoinstaller.cgi --force=rvsitebuilder