diff -r 000000000000 -r 6474c204b198 mobile/android/base/background/fxa/FxAccountClientException.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/background/fxa/FxAccountClientException.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,127 @@
+/* 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.background.fxa;
+
+import org.mozilla.gecko.R;
+import org.mozilla.gecko.sync.ExtendedJSONObject;
+import org.mozilla.gecko.sync.HTTPFailureException;
+import org.mozilla.gecko.sync.net.SyncStorageResponse;
+
+import ch.boye.httpclientandroidlib.HttpResponse;
+import ch.boye.httpclientandroidlib.HttpStatus;
+
+/**
+ * From <a href="https://github.com/mozilla/fxa-auth-server/blob/master/docs/api.md">https://github.com/mozilla/fxa-auth-server/blob/master/docs/api.md</a>.
+ */
+public class FxAccountClientException extends Exception {
+  private static final long serialVersionUID = 7953459541558266597L;
+
+  public FxAccountClientException(String detailMessage) {
+    super(detailMessage);
+  }
+
+  public FxAccountClientException(Exception e) {
+    super(e);
+  }
+
+  public static class FxAccountClientRemoteException extends FxAccountClientException {
+    private static final long serialVersionUID = 2209313149952001097L;
+
+    public final HttpResponse response;
+    public final long httpStatusCode;
+    public final long apiErrorNumber;
+    public final String error;
+    public final String message;
+    public final String info;
+    public final ExtendedJSONObject body;
+
+    public FxAccountClientRemoteException(HttpResponse response, long httpStatusCode, long apiErrorNumber, String error, String message, String info, ExtendedJSONObject body) {
+      super(new HTTPFailureException(new SyncStorageResponse(response)));
+      if (body == null) {
+        throw new IllegalArgumentException("body must not be null");
+      }
+      this.response = response;
+      this.httpStatusCode = httpStatusCode;
+      this.apiErrorNumber = apiErrorNumber;
+      this.error = error;
+      this.message = message;
+      this.info = info;
+      this.body = body;
+    }
+
+    @Override
+    public String toString() {
+      return "<FxAccountClientRemoteException " + this.httpStatusCode + " [" + this.apiErrorNumber + "]: " + this.message + ">";
+    }
+
+    public boolean isInvalidAuthentication() {
+      return httpStatusCode == HttpStatus.SC_UNAUTHORIZED;
+    }
+
+    public boolean isAccountAlreadyExists() {
+      return apiErrorNumber == FxAccountRemoteError.ATTEMPT_TO_CREATE_AN_ACCOUNT_THAT_ALREADY_EXISTS;
+    }
+
+    public boolean isAccountDoesNotExist() {
+      return apiErrorNumber == FxAccountRemoteError.ATTEMPT_TO_ACCESS_AN_ACCOUNT_THAT_DOES_NOT_EXIST;
+    }
+
+    public boolean isBadPassword() {
+      return apiErrorNumber == FxAccountRemoteError.INCORRECT_PASSWORD;
+    }
+
+    public boolean isUnverified() {
+      return apiErrorNumber == FxAccountRemoteError.ATTEMPT_TO_OPERATE_ON_AN_UNVERIFIED_ACCOUNT;
+    }
+
+    public boolean isUpgradeRequired() {
+      return
+          apiErrorNumber == FxAccountRemoteError.ENDPOINT_IS_NO_LONGER_SUPPORTED ||
+          apiErrorNumber == FxAccountRemoteError.INCORRECT_LOGIN_METHOD_FOR_THIS_ACCOUNT ||
+          apiErrorNumber == FxAccountRemoteError.INCORRECT_KEY_RETRIEVAL_METHOD_FOR_THIS_ACCOUNT ||
+          apiErrorNumber == FxAccountRemoteError.INCORRECT_API_VERSION_FOR_THIS_ACCOUNT;
+    }
+
+    public boolean isTooManyRequests() {
+      return apiErrorNumber == FxAccountRemoteError.CLIENT_HAS_SENT_TOO_MANY_REQUESTS;
+    }
+
+    public boolean isServerUnavailable() {
+      return apiErrorNumber == FxAccountRemoteError.SERVICE_TEMPORARILY_UNAVAILABLE_DUE_TO_HIGH_LOAD;
+    }
+
+    public boolean isBadEmailCase() {
+      return apiErrorNumber == FxAccountRemoteError.INCORRECT_EMAIL_CASE;
+    }
+
+    public int getErrorMessageStringResource() {
+      if (isUpgradeRequired()) {
+        return R.string.fxaccount_remote_error_UPGRADE_REQUIRED;
+      } else if (isAccountAlreadyExists()) {
+        return R.string.fxaccount_remote_error_ATTEMPT_TO_CREATE_AN_ACCOUNT_THAT_ALREADY_EXISTS;
+      } else if (isAccountDoesNotExist()) {
+        return R.string.fxaccount_remote_error_ATTEMPT_TO_ACCESS_AN_ACCOUNT_THAT_DOES_NOT_EXIST;
+      } else if (isBadPassword()) {
+        return R.string.fxaccount_remote_error_INCORRECT_PASSWORD;
+      } else if (isUnverified()) {
+        return R.string.fxaccount_remote_error_ATTEMPT_TO_OPERATE_ON_AN_UNVERIFIED_ACCOUNT;
+      } else if (isTooManyRequests()) {
+        return R.string.fxaccount_remote_error_CLIENT_HAS_SENT_TOO_MANY_REQUESTS;
+      } else if (isServerUnavailable()) {
+        return R.string.fxaccount_remote_error_SERVICE_TEMPORARILY_UNAVAILABLE_TO_DUE_HIGH_LOAD;
+      } else {
+        return R.string.fxaccount_remote_error_UNKNOWN_ERROR;
+      }
+    }
+  }
+
+  public static class FxAccountClientMalformedResponseException extends FxAccountClientRemoteException {
+    private static final long serialVersionUID = 2209313149952001098L;
+
+    public FxAccountClientMalformedResponseException(HttpResponse response) {
+      super(response, 0, FxAccountRemoteError.UNKNOWN_ERROR, "Response malformed", "Response malformed", "Response malformed", new ExtendedJSONObject());
+    }
+  }
+}