AlexT
Dolphin 7.1 is compatible with HTTPS, however it was some small fixes regarding HTTPS support in Dolphin 7.2, so it's better to upgrade to Dolphin 7.2 before moving site to HTTPS.

Most probably you didn't clear caches after applying HTTPS on your site, so you've got all these errors.
 
 
Below is the legacy version of the Boonex site, maintained for Dolphin.Pro 7.x support.
The new Dolphin solution is powered by UNA Community Management System.
PET:0.061041116714478