I'm having the same issue. API calls to/home/me return ' unknown error has occurred. You can verify that the read_stream given before all API calls.
Interesting, I have an application that was months ago, he can't access/home/me without any problems. I then copied over the exact code my application to the newly created (created recently on app developers), swapped APP_ID, APP_SECRET with the appropriate values. /Home/calls return ' unknown error has occurred. I did the application settings all resemble each other as possible. However, new applications for certain settings from sinking so developers could not exactly match the settings.
Due to the scenario above, it looks like a really bizarre problem at Facebook. Assistance from someone on Facebook be but appreciated.