Flutter Facebook login responds with Http status error [500]

Question

I have added Facebook login to my flutter project and its logging in successfully but the problem is, The user is not able to enter the home screen of the application and stays back on the login screen. It is responding as Http status error [500].

Below is the code for Facebook login/authentication:

void doFacebookSignIn() async{

    print("FaceBook Clicked");

try {
      final result =
      await FacebookAuth.i.login(permissions: ['email']);
      if (result.status == LoginStatus.success) {
        final userData = await FacebookAuth.i.getUserData();
        print(userData);
        hitFacebookApi(result.accessToken.token);
        await FacebookAuth.i.logOut();
        if (result.status == LoginStatus.cancelled) {
          ToastUtils.showCustomToast(context, "cancelled", Colors.white , MyColors.primaryColor);
        }
        if (result.status == LoginStatus.failed) {
          ToastUtils.showCustomToast(context, result.message, Colors.white , MyColors.primaryColor);
        }
      }
    } catch (error) {
      print(error);
    }
 }

Code for entering from Login to Home screen:

void hitFacebookApi(String token) {
    CommonApis().logInWithFB(
        {"token": "$token"}, CommonUtils.getLanguage(context) == "english")
        .then((value) async{
      if (value is Map) {
        String  fullToken = "Bearer ${value['token']}";
        ApiUtils.headerWithToken.update("Authorization",(value)=> fullToken);
        await userData.save(fullToken, "client");
        await userService.getProfile();
        Navigator.pushAndRemoveUntil(context,PageTransition(type: PageTransitionType.fade, child:  ClientMain()), (Route<dynamic> route) => false);
      } else {
        ToastUtils.showCustomToast(
            context, value, Colors.white, MyColors.primaryColor);
        print("the cause "+value);
      }
    });
  }

Code for API method:

Future<dynamic> logInWithFB(dynamic data ,bool isEnglish) async{
    try{
      final response=  await Dio().post("${ApiUtils.BaseApiUrl}/auth/social/facebook",data: data,options: Options(headers: ApiUtils.headerForRegister ));
      if(response.statusCode==200){
        return {
          "token" : response.data['token']
        };
      }
      else{
        return isEnglish?response.data['error']['en']:response.data['error']['ar'];
      }
    }on DioError catch(e) {
      if(e.response !=null) {
        return e.message;
      }
    }
  }