Mine is a FB App based on canvas. Facing an issue both on Chrome and Firefox, (although usually Chrome):

1.When I hit my approved fb app secure URL on a new incognito Chrome window (<https://apps.facebook.com/myfbappnamespace/>), the below error comes only for the first time, and when I refresh the page the error is gone (most of the times)

> 
> The page at about:blank displayed insecure content from
>  <http://static.ak.facebook.com/connect/xd_arbiter.php?version=18#cb=f2e4fe7b>…os.com%2Ff4aeadb2&domain=www.mydomain.com&relation=parent&error=unknown\_user.
> 
> 
> Unsafe JavaScript attempt to access frame with URL
>  <http://www.mydomain.com/control/myfacebookapp/> from frame with URL
>  <http://static.ak.facebook.com/connect/xd_arbiter.php?version=18#cb=f2e4fe7b>…os.com%2Ff4aeadb2&domain=www.mydomain.com&relation=parent&error=unknown\_user.
>  The frame requesting access set 'document.domain' to 'facebook.com',
>  but the frame being accessed did not. Both must set 'document.domain'
>  to the same value to allow access.  
> 
>  xd\_arbiter.php:18
> 
> 
> Unsafe JavaScript attempt to access frame with URL
>  <http://www.mydomain.com/control/myfacebookapp/> from frame with URL
>  <http://static.ak.facebook.com/connect/xd_arbiter.php?version=18#cb=f2e4fe7b>…os.com%2Ff4aeadb2&domain=www.mydomain.com&relation=parent&error=unknown\_user.
>  The frame requesting access set 'document.domain' to 'facebook.com',
>  but the frame being accessed did not. Both must set 'document.domain'
>  to the same value to allow access. xd\_arbiter.php:18
> 
> 
> 

2.When I try the http url(<http://apps.facebook.com/myfbappnamespace/>), the error shown in console is:

> 
> Unsafe JavaScript attempt to access frame with URL
>  <http://apps.facebook.com/myfbappnamespace/> from frame with URL
>  <https://s-static.ak.facebook.com/connect/xd_arbiter.php?version=18#channel=>…Fcontrol%2Ffacebookappchannelurl%3Ffb\_xd\_fragment%23xd\_sig%3Df23e84e85c%26.
>  The frame requesting access has a protocol of 'https', the frame being
>  accessed has a protocol of 'http'. Protocols must match.
> 
> 
> 

Now when I login to my fb account to see what happens with these errors, they are gone, again only sometimes. I know that I am using "most of the times" and "sometimes" here in my query but that is exactly what is happening with me. I have also searched forums and realize that fb has already fixed this old issue which was supposed to be chrome specific. I have made sure that my FB.init and other calls are location.protocol value specific. Also configured correct values in canvas url (http) and secure canvas url (https). Also tried with both the settings:
Account Settings -> Security -> Secure Browsing -> (Enabled as well as Disabled)

Can somebody please help if I am missing something somewhere?