If you have clients that are experiencing permission / SSL errors when visiting the embedded application, the user can temporarily use the Facebook page in standard HTTP (Non-SSL mode) by following the procedure below. The SSL options can be turned back on by following the same procedure and ticking the enable option.
On the Facebook site, go to the security settings:
1) Start by visiting your account settings, the gear icon highlighted in green (1.).
2) Click the security settings link (2. above).
3) Locate the checkbox highlighted in the image below (Browse Facebook on a secure connection (https) when possible), and untick the option then save changes.
4) Logout of Facebook, then back in again, you should now be viewing the page in 'non-SSL' mode.
The address bar should now reflect the change from:
This may differ slightly from browser to browser, and will only effect the Facebook site.
This will then allow any non-HTTPS content to be delivered, within the Facebook page, through to the browser without triggering warnings or automatically being blocked by certain browsers or local security policies.