SymptomsThe Parallels Plesk Control Panel interface is not displaying properly. After a successful login, only a blank page is displayed. However, if the frame content (e.g., https://<HOSTNAME>:8443/admin/) is opened in a separate window, the interface displays properly.
CauseSuch an issue may occur due to custom IIS configuration. In particular, it may occur if HTTP Response Header settings in IIS are preventing Parallels Plesk Control Panel from working in frames.
Resolution1. Open Internet Information Services (IIS) Manager and click on Sites -> PleskControlPanel in the left panel.
2. In the main frame on the right, go to HTTP Response Headers in the IIS section.
3. Find the X-FRAME-OPTIONS header in the list and change its value from DENY to ALLOW.