WHMCS cannot connect to Plesk in PCI compliance mode

[websavers]

Hey there,

 

After applying the necessary changes to the Plesk configuration for PCI compliance that essentially disable SSLv3 and TLSv1 (leaving only TLSv1.1 and TLSv1.2 as an option), WHMCS is no longer able to communicate with Plesk. It provides this error when attempting to do so:

 

Error code: 0. Error message: Curl error: [35] SSL connect error.

 

Is there something being passed to curl that is requiring SSLv3 or TLSv1.0 only?

 

We're using openssl-1.0.1e-42.el6.x86_64 on CentOS 6.7, which most definitely supports the latest TLS protocol versions.

 

Plesk: 12.0.18 Update #69

WHMCS: 6.1.1