This error occurs when the app doesn't have the appropriate permissions to your Fitbit profile. Please do the following.
- Log into your Fitbit.com account using your web browser.
- Click on "Settings" at the top right of your screen
- Click on "Applications" in the left hand menu.
- On the right you should see "My Applications". Scroll down and find myFitnessSync.
- Under "Access" you should see "food and water logs, heart rate, sleep, activity and exercise, weight, profile". (Profile is probably missing)
- Click "Revoke Access"
- Launch our App again. Go to Settings and click "Logout"
- Click "Login". Make sure to keep "profile" checked along with the other fields.