diff --git a/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticator.java b/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticator.java
index 4612d1a..a5624ca 100644
--- a/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticator.java
+++ b/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticator.java
@@ -4,6 +4,7 @@ import android.accounts.AbstractAccountAuthenticator;
 import android.accounts.Account;
 import android.accounts.AccountAuthenticatorResponse;
 import android.accounts.AccountManager;
+import android.accounts.AccountsException;
 import android.accounts.NetworkErrorException;
 import android.content.Context;
 import android.content.Intent;
@@ -12,9 +13,13 @@ import android.text.TextUtils;
 
 import java.util.concurrent.ExecutionException;
 
+import de.sebse.fuplanner.tools.CustomAccountManager;
+import de.sebse.fuplanner.tools.logging.Logger;
+
 public class FUAuthenticator extends AbstractAccountAuthenticator {
 
     private final Context mContext;
+    private Logger log = new Logger(this);
 
     public FUAuthenticator(Context context) {
         super(context);
@@ -28,6 +33,18 @@ public class FUAuthenticator extends AbstractAccountAuthenticator {
 
     @Override
     public Bundle addAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType, String[] requiredFeatures, Bundle options) throws NetworkErrorException {
+        final AccountManager am = AccountManager.get(mContext);
+        log.d((Object[]) am.getAccountsByType(accountType));
+        log.d(am.getAccountsByType(accountType).length);
+        if (am.getAccountsByType(accountType).length > 0) {
+            final Intent intent = new Intent(mContext, FUAuthenticatorActivity.class);
+            intent.putExtra(AccountManager.KEY_ERROR_CODE, AccountManager.ERROR_CODE_UNSUPPORTED_OPERATION);
+            intent.putExtra(AccountManager.KEY_ERROR_MESSAGE, "Already an account added!");
+            final Bundle bundle = new Bundle();
+            bundle.putParcelable(AccountManager.KEY_INTENT, intent);
+            return bundle;
+        }
+
         final Intent intent = new Intent(mContext, FUAuthenticatorActivity.class);
         intent.putExtra(FUAuthenticatorActivity.ARG_ACCOUNT_TYPE, accountType);
         intent.putExtra(FUAuthenticatorActivity.ARG_AUTH_TYPE, authTokenType);
diff --git a/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticatorActivity.java b/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticatorActivity.java
index 94af73e..8cb2681 100644
--- a/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticatorActivity.java
+++ b/app/src/main/java/de/sebse/fuplanner/services/fulogin/FUAuthenticatorActivity.java
@@ -55,6 +55,7 @@ public class FUAuthenticatorActivity extends AccountAuthenticatorActivity {
 
         mAccountType = getIntent().getStringExtra(ARG_ACCOUNT_TYPE);
         mAuthTokenType = getIntent().getStringExtra(ARG_AUTH_TYPE);
+        mAuthTokenType = mAuthTokenType != null ? mAuthTokenType : AccountGeneral.AUTHTOKEN_TYPE_KVV;
         mIsAddingNewAccount = getIntent().getBooleanExtra(ARG_IS_ADDING_NEW_ACCOUNT, false);
 
         setContentView(R.layout.activity_fu_authenticator);
diff --git a/app/src/main/java/de/sebse/fuplanner/services/fulogin/UserLoginTask.java b/app/src/main/java/de/sebse/fuplanner/services/fulogin/UserLoginTask.java
index 865cf73..25827ee 100644
--- a/app/src/main/java/de/sebse/fuplanner/services/fulogin/UserLoginTask.java
+++ b/app/src/main/java/de/sebse/fuplanner/services/fulogin/UserLoginTask.java
@@ -18,6 +18,7 @@ import de.sebse.fuplanner.services.kvv.sync.BBLogin;
 import de.sebse.fuplanner.services.kvv.sync.FULogin;
 import de.sebse.fuplanner.services.kvv.sync.KVVLogin;
 import de.sebse.fuplanner.tools.logging.Logger;
+import de.sebse.fuplanner.tools.network.NetworkError;
 import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
 
 
@@ -46,7 +47,7 @@ public class UserLoginTask extends AsyncTask<Void, Void, String> {
     @Nullable
     private FUAuthenticatorActivity mActivity;
 
-    UserLoginTask(String username, String password, String tokenType, @NotNull Context context) {
+    UserLoginTask(String username, String password, @NotNull String tokenType, @NotNull Context context) {
         mUsername = username;
         mPassword = password;
         mTokenType = tokenType;
@@ -95,6 +96,7 @@ public class UserLoginTask extends AsyncTask<Void, Void, String> {
                 }, errorFunc);
                 break;
             default:
+                errorFunc.onError(new NetworkError(104100, 400, "Invalid auth token type"));
                 return null;
         }
         try {