Facebook/WebGL persistent data storage + Safari fail

Target Platforms Web
1

I’ve just received this error when trying to sync to the file system:

undefined is not an object (evaluating 'IDBFS.indexedDB().open')

My JSLIB:

var HandleIO = {
    WindowAlert : function(message)
    {
        window.alert(Pointer_stringify(message));
    },
    SyncFiles : function()
    {
        window.alert('syncfiles called');
        FS.syncfs(false,function (err) {
            window.alert('syncfiles finished:'+err);
        });
    }
};

mergeInto(LibraryManager.library, HandleIO);

My save code

 public void Save(){
        try
        {
            BinaryFormatter bin = new BinaryFormatter();
            using( FileStream file = File.Open( this.filename, FileMode.OpenOrCreate ) )
            {
                bin.Serialize( file, this.data );
                bin.Serialize( file, this.nVersionNumber );
            }
        }
        catch( Exception ex )
        {
            Debug.Log( String.Format("Failed to save file {0}:{1}", filename,ex.ToString() ) );
        }

        if( Application.platform==RuntimePlatform.WebGLPlayer )
        {
            // if webgl - synch javascript
            SyncFiles();
        }
    }

Browser: Safari10.1
Seems fine on Chrome.
Unity:5.6
What can I do to fix this?

2

I believe this is because Safari by default blocks third party cookies and other data (like indexedDB and local storage).
You can change this in Safari Privacy settings but it may of course not be feasible to force all your end users to do so.

3

Looking at the JS console output in Facebook with Safari:

I found this thread - same issue! Looks like it’s still a problem for Safari using Facebook with WebGL and iFrame.
https://forum.unity3d.com/threads/playerprefs-will-not-be-saved.319348/

Not sure what my options are for Safari users.