Prior to SoluteDNS v0.2.5 we do not recommend you to upgrade to WHMCS v7. In order to upgrade to WHMCS v7 we recommend to upgrade to SoluteDNS v0.2.5 or later.
There for we do give a considered upgrade recommendation. Please consider the advised steps prior to upgrading.
WHMCS: v7.0.0 (Beta 1)
SoluteDNS: v0.2.4 (current release)