Running react-native-fbsdk ^0.3.0, and Xcode 8 beta with iOS 10, I kept getting the Login Error in the Title, ECOM.FACEBOOK.SDK.LOGIN308 when the following code was executed:
LoginManager.logInWithReadPermissions([
'public_profile'
]).then((result) => {
if (result.isCancelled) {
alert('Login cancelled');
} else {
alert('Login success with permissions: '
+ result.grantedPermissions.toString());
}
}, function (error) {
console.log(error);
alert('Login fail with error: ' + error);
});
Under the _capabilities_ section of the app, you need to enable _Keychain Sharing_ for you application. Upon enabling this.

iOS SDK released 4.15.1 to support iOS 10. Make sure you use it. https://developers.facebook.com/docs/ios/change-log-4.x
Most helpful comment
iOS SDK released 4.15.1 to support iOS 10. Make sure you use it. https://developers.facebook.com/docs/ios/change-log-4.x