Google.GData.Client.GDataRequestException - Authentication suddenly fails in old code

Question

I\'m suddenly starting to get the following exception when attempting to authenticate and access a spreadsheet on Google drive:

Unhandled Exception: G

Answer 1

I've managed to solve this by using this solution with Service Account with oAuth2.0 Accessing older GData APIs (Spreadsheet API) using OAuth 2 and a service account

The solution: 1. Create Project and Google Service Account in https://console.developers.google.com/project

2. Generate your p12 key.
3. Allow APIs in Developer console you want to use (basically we are going to use old API, so you can skip this step, but just in case)
4. Use the code below (.NET Framework 4.5!)
5. Also don't forget to grant "youraccount@developer.gserviceaccount.com" access to your spreadsheet document as you grant permissions for usual users by pressing Share.

Code:

using System.Security.Cryptography.X509Certificates;
using Google.GData.Client;
using Google.GData.Extensions;
using Google.GData.Spreadsheets;
using Google.Apis.Auth.OAuth2;

string keyFilePath = @"C:\key.p12";    // found in developer console
string serviceAccountEmail = "youraccount@developer.gserviceaccount.com";   // found in developer console
var certificate = new X509Certificate2(keyFilePath, "notasecret", X509KeyStorageFlags.Exportable);

ServiceAccountCredential credential = new ServiceAccountCredential(new ServiceAccountCredential.Initializer(serviceAccountEmail) //create credential using certificate
        {
            Scopes = new[] { "https://spreadsheets.google.com/feeds/" } //this scopr is for spreadsheets, check google scope FAQ for others
        }.FromCertificate(certificate));

credential.RequestAccessTokenAsync(System.Threading.CancellationToken.None).Wait(); //request token

var requestFactory = new GDataRequestFactory("Some Name"); 
requestFactory.CustomHeaders.Add(string.Format("Authorization: Bearer {0}", credential.Token.AccessToken));

SpreadsheetsService myService = new SpreadsheetsService("You App Name"); //create your old service
myService.RequestFactory = requestFactory; //add new request factory to your old service

SpreadsheetQuery query = new SpreadsheetQuery(); //do the job as you done it before
SpreadsheetFeed feed = myService.Query(query);