--- a/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/FxAccountDeviceRegistrator.java
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/FxAccountDeviceRegistrator.java
@@ -13,17 +13,16 @@ import android.util.Log;
 import org.mozilla.gecko.background.common.log.Logger;
 import org.mozilla.gecko.background.fxa.FxAccountClient;
 import org.mozilla.gecko.background.fxa.FxAccountClient20;
 import org.mozilla.gecko.background.fxa.FxAccountClient20.AccountStatusResponse;
 import org.mozilla.gecko.background.fxa.FxAccountClient20.RequestDelegate;
 import org.mozilla.gecko.background.fxa.FxAccountClientException.FxAccountClientRemoteException;
 import org.mozilla.gecko.background.fxa.FxAccountRemoteError;
 import org.mozilla.gecko.fxa.authenticator.AndroidFxAccount;
-import org.mozilla.gecko.fxa.authenticator.AndroidFxAccount.InvalidFxAState;
 import org.mozilla.gecko.fxa.login.State;
 import org.mozilla.gecko.sync.SharedPreferencesClientsDataDelegate;
 import org.mozilla.gecko.util.BundleEventListener;
 import org.mozilla.gecko.util.EventCallback;
 import org.mozilla.gecko.util.GeckoBundle;
 
 import java.io.UnsupportedEncodingException;
 import java.lang.ref.WeakReference;
@@ -118,45 +117,47 @@ public class FxAccountDeviceRegistrator 
     final AndroidFxAccount fxAccount = AndroidFxAccount.fromContext(context);
     intent.putExtra("org.mozilla.gecko.intent.PROFILE_NAME", fxAccount.getProfile());
     return intent;
   }
 
   @Override
   public void handleMessage(String event, GeckoBundle message, EventCallback callback) {
     if ("FxAccountsPush:Subscribe:Response".equals(event)) {
-      try {
-        doFxaRegistration(message.getBundle("subscription"));
-      } catch (InvalidFxAState e) {
-        Log.d(LOG_TAG, "Invalid state when trying to register with FxA ", e);
-      }
+      doFxaRegistration(message.getBundle("subscription"));
     } else {
       Log.e(LOG_TAG, "No action defined for " + event);
     }
   }
 
-  private void doFxaRegistration(GeckoBundle subscription) throws InvalidFxAState {
+  private void doFxaRegistration(GeckoBundle subscription) {
     final Context context = this.context.get();
     if (this.context == null) {
       throw new IllegalStateException("Application context has been gc'ed");
     }
     doFxaRegistration(context, subscription, true);
   }
 
-  private static void doFxaRegistration(final Context context, final GeckoBundle subscription, final boolean allowRecursion) throws InvalidFxAState {
+  private static void doFxaRegistration(final Context context, final GeckoBundle subscription, final boolean allowRecursion) {
     String pushCallback = subscription.getString("pushCallback");
     String pushPublicKey = subscription.getString("pushPublicKey");
     String pushAuthKey = subscription.getString("pushAuthKey");
 
     final AndroidFxAccount fxAccount = AndroidFxAccount.fromContext(context);
     if (fxAccount == null) {
       Log.e(LOG_TAG, "AndroidFxAccount is null");
       return;
     }
-    final byte[] sessionToken = fxAccount.getSessionToken();
+    final byte[] sessionToken;
+    try {
+      sessionToken = fxAccount.getState().getSessionToken();
+    } catch (State.NotASessionTokenState e) {
+      Log.e(LOG_TAG, "Could not get a session token", e);
+      return;
+    }
     final FxAccountDevice device;
     String deviceId = fxAccount.getDeviceId();
     String clientName = getClientName(fxAccount, context);
     if (TextUtils.isEmpty(deviceId)) {
       Log.i(LOG_TAG, "Attempting registration for a new device");
       device = FxAccountDevice.forRegister(clientName, "mobile", pushCallback, pushPublicKey, pushAuthKey);
     } else {
       Log.i(LOG_TAG, "Attempting registration for an existing device");
@@ -291,23 +292,18 @@ public class FxAccountDeviceRegistrator 
       public void handleSuccess(FxAccountDevice[] devices) {
         for (FxAccountDevice device : devices) {
           if (device.isCurrentDevice) {
             fxAccount.setFxAUserData(device.id, 0, 0L); // Reset device registration version/timestamp
             if (!allowRecursion) {
               Log.d(LOG_TAG, "Failure to register a device on the second try");
               break;
             }
-            try {
-              doFxaRegistration(context, subscription, false);
-              return;
-            } catch (InvalidFxAState e) {
-              Log.d(LOG_TAG, "Invalid state when trying to recover from a session conflict ", e);
-              break;
-            }
+            doFxaRegistration(context, subscription, false);
+            return;
           }
         }
         onError();
       }
     });
   }
 
   private void setupListeners() throws ClassNotFoundException, NoSuchMethodException,

--- a/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/authenticator/AndroidFxAccount.java
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/authenticator/AndroidFxAccount.java
@@ -25,17 +25,16 @@ import org.mozilla.gecko.background.comm
 import org.mozilla.gecko.background.common.log.Logger;
 import org.mozilla.gecko.background.fxa.FxAccountUtils;
 import org.mozilla.gecko.db.BrowserContract;
 import org.mozilla.gecko.fxa.FirefoxAccounts;
 import org.mozilla.gecko.fxa.FxAccountConstants;
 import org.mozilla.gecko.fxa.login.State;
 import org.mozilla.gecko.fxa.login.State.StateLabel;
 import org.mozilla.gecko.fxa.login.StateFactory;
-import org.mozilla.gecko.fxa.login.TokensAndKeysState;
 import org.mozilla.gecko.fxa.sync.FxAccountProfileService;
 import org.mozilla.gecko.sync.ExtendedJSONObject;
 import org.mozilla.gecko.sync.Utils;
 import org.mozilla.gecko.sync.setup.Constants;
 import org.mozilla.gecko.util.ThreadUtils;
 
 import java.io.UnsupportedEncodingException;
 import java.net.URISyntaxException;
@@ -605,34 +604,16 @@ public class AndroidFxAccount {
       StateLabel stateLabel = StateLabel.valueOf(stateLabelString);
       Logger.debug(LOG_TAG, "Account is in state " + stateLabel);
       return StateFactory.fromJSONObject(stateLabel, new ExtendedJSONObject(stateString));
     } catch (Exception e) {
       throw new IllegalStateException("could not get state", e);
     }
   }
 
-  public byte[] getSessionToken() throws InvalidFxAState {
-    State state = getState();
-    StateLabel stateLabel = state.getStateLabel();
-    if (stateLabel == StateLabel.Cohabiting || stateLabel == StateLabel.Married) {
-      TokensAndKeysState tokensAndKeysState = (TokensAndKeysState) state;
-      return tokensAndKeysState.getSessionToken();
-    }
-    throw new InvalidFxAState("Cannot get sessionToken: not in a TokensAndKeysState state");
-  }
-
-  public static class InvalidFxAState extends Exception {
-    private static final long serialVersionUID = -8537626959811195978L;
-
-    public InvalidFxAState(String message) {
-      super(message);
-    }
-  }
-
   /**
    * <b>For debugging only!</b>
    */
   public void dump() {
     if (!FxAccountUtils.LOG_PERSONAL_INFORMATION) {
       return;
     }
     ExtendedJSONObject o = toJSONObject();
@@ -690,19 +671,19 @@ public class AndroidFxAccount {
     }
 
     // Update intent with tokens and service URI.
     intent.putExtra(FxAccountConstants.ACCOUNT_OAUTH_SERVICE_ENDPOINT_KEY, getOAuthServerURI());
     // Deleted broadcasts are package-private, so there's no security risk include the tokens in the extras
     intent.putExtra(FxAccountConstants.ACCOUNT_DELETED_INTENT_ACCOUNT_AUTH_TOKENS, tokens.toArray(new String[tokens.size()]));
 
     try {
-      intent.putExtra(FxAccountConstants.ACCOUNT_DELETED_INTENT_ACCOUNT_SESSION_TOKEN, getSessionToken());
-    } catch (InvalidFxAState e) {
-      Logger.warn(LOG_TAG, "Could not get a session token, ignoring.", e);
+      intent.putExtra(FxAccountConstants.ACCOUNT_DELETED_INTENT_ACCOUNT_SESSION_TOKEN, getState().getSessionToken());
+    } catch (State.NotASessionTokenState e) {
+      // Ignore, if sessionToken is null we won't try to do anything anyway.
     }
     intent.putExtra(FxAccountConstants.ACCOUNT_DELETED_INTENT_ACCOUNT_SERVER_URI, getAccountServerURI());
     intent.putExtra(FxAccountConstants.ACCOUNT_DELETED_INTENT_ACCOUNT_DEVICE_ID, getDeviceId());
 
     return intent;
   }
 
   /**

--- a/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/login/Engaged.java
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/login/Engaged.java
@@ -1,28 +1,28 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package org.mozilla.gecko.fxa.login;
 
-import java.security.NoSuchAlgorithmException;
-
 import org.mozilla.gecko.background.fxa.FxAccountClient20.TwoKeys;
 import org.mozilla.gecko.background.fxa.FxAccountUtils;
 import org.mozilla.gecko.browserid.BrowserIDKeyPair;
 import org.mozilla.gecko.fxa.login.FxAccountLoginStateMachine.ExecuteDelegate;
 import org.mozilla.gecko.fxa.login.FxAccountLoginTransition.AccountVerified;
 import org.mozilla.gecko.fxa.login.FxAccountLoginTransition.LocalError;
 import org.mozilla.gecko.fxa.login.FxAccountLoginTransition.LogMessage;
 import org.mozilla.gecko.fxa.login.FxAccountLoginTransition.RemoteError;
 import org.mozilla.gecko.fxa.login.FxAccountLoginTransition.Transition;
 import org.mozilla.gecko.sync.ExtendedJSONObject;
 import org.mozilla.gecko.sync.Utils;
 
+import java.security.NoSuchAlgorithmException;
+
 public class Engaged extends State {
   private static final String LOG_TAG = Engaged.class.getSimpleName();
 
   protected final byte[] sessionToken;
   protected final byte[] keyFetchToken;
   protected final byte[] unwrapkB;
 
   public Engaged(String email, String uid, boolean verified, byte[] unwrapkB, byte[] sessionToken, byte[] keyFetchToken) {
@@ -80,12 +80,13 @@ public class Engaged extends State {
   @Override
   public Action getNeededAction() {
     if (!verified) {
       return Action.NeedsVerification;
     }
     return Action.None;
   }
 
+  @Override
   public byte[] getSessionToken() {
     return sessionToken;
   }
 }

--- a/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/login/State.java
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/login/State.java
@@ -6,16 +6,25 @@ package org.mozilla.gecko.fxa.login;
 
 import org.mozilla.gecko.fxa.login.FxAccountLoginStateMachine.ExecuteDelegate;
 import org.mozilla.gecko.sync.ExtendedJSONObject;
 import org.mozilla.gecko.sync.Utils;
 
 public abstract class State {
   public static final long CURRENT_VERSION = 3L;
 
+  public class NotASessionTokenState extends Exception {
+
+    private static final long serialVersionUID = 8628129091996684799L;
+
+    public NotASessionTokenState(String message) {
+      super(message);
+    }
+  }
+
   public enum StateLabel {
     Engaged,
     Cohabiting,
     Married,
     Separated,
     Doghouse,
     MigratedFromSync11,
   }
@@ -64,9 +73,14 @@ public abstract class State {
 
   public State makeMigratedFromSync11State(String password) {
     return new MigratedFromSync11(email, uid, verified, password);
   }
 
   public abstract void execute(ExecuteDelegate delegate);
 
   public abstract Action getNeededAction();
+
+  // Should be overridden in states that have a sessionToken
+  public byte[] getSessionToken() throws NotASessionTokenState {
+    throw new NotASessionTokenState("Cannot get a session token in " + stateLabel);
+  }
 }

--- a/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/login/TokensAndKeysState.java
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/login/TokensAndKeysState.java
@@ -29,16 +29,17 @@ public abstract class TokensAndKeysState
     // Fields are non-null by constructor.
     o.put("sessionToken", Utils.byte2Hex(sessionToken));
     o.put("kA", Utils.byte2Hex(kA));
     o.put("kB", Utils.byte2Hex(kB));
     o.put("keyPair", keyPair.toJSONObject());
     return o;
   }
 
+  @Override
   public byte[] getSessionToken() {
     return sessionToken;
   }
 
   @Override
   public Action getNeededAction() {
     return Action.None;
   }

--- a/mobile/android/services/src/main/java/org/mozilla/gecko/sync/stage/SyncClientsEngineStage.java
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/stage/SyncClientsEngineStage.java
@@ -24,16 +24,17 @@ import org.json.simple.JSONArray;
 import org.json.simple.JSONObject;
 import org.mozilla.gecko.AppConstants;
 import org.mozilla.gecko.background.common.log.Logger;
 import org.mozilla.gecko.background.fxa.FxAccountClient;
 import org.mozilla.gecko.background.fxa.FxAccountClient20;
 import org.mozilla.gecko.background.fxa.FxAccountClientException;
 import org.mozilla.gecko.fxa.FirefoxAccounts;
 import org.mozilla.gecko.fxa.authenticator.AndroidFxAccount;
+import org.mozilla.gecko.fxa.login.State;
 import org.mozilla.gecko.sync.CommandProcessor;
 import org.mozilla.gecko.sync.CommandProcessor.Command;
 import org.mozilla.gecko.sync.CryptoRecord;
 import org.mozilla.gecko.sync.ExtendedJSONObject;
 import org.mozilla.gecko.sync.HTTPFailureException;
 import org.mozilla.gecko.sync.NoCollectionKeysSetException;
 import org.mozilla.gecko.sync.Utils;
 import org.mozilla.gecko.sync.crypto.CryptoException;
@@ -189,19 +190,21 @@ public class SyncClientsEngineStage exte
         Log.e(LOG_TAG, "Can't notify other clients: no account");
         return;
       }
       final AndroidFxAccount fxAccount = new AndroidFxAccount(context, account);
       final ExtendedJSONObject payload = createNotifyDevicesPayload();
 
       final byte[] sessionToken;
       try {
-        sessionToken = fxAccount.getSessionToken();
-      } catch (AndroidFxAccount.InvalidFxAState invalidFxAState) {
-        Log.e(LOG_TAG, "Could not get session token", invalidFxAState);
+        sessionToken = fxAccount.getState().getSessionToken();
+      } catch (State.NotASessionTokenState e) {
+        // Most of the time we should never reach this, but there can be races with the account
+        // state, so better safe than sorry.
+        Log.e(LOG_TAG, "Could not get a session token during Sync (?)", e);
         return;
       }
 
       // API doc : https://github.com/mozilla/fxa-auth-server/blob/master/docs/api.md#post-v1accountdevicesnotify
       final FxAccountClient fxAccountClient = new FxAccountClient20(fxAccount.getAccountServerURI(), executor);
       fxAccountClient.notifyDevices(sessionToken, devicesToNotify, payload, NOTIFY_TAB_SENT_TTL_SECS, new FxAccountClient20.RequestDelegate<ExtendedJSONObject>() {
         @Override
         public void handleError(Exception e) {