--- a/browser/components/extensions/test/browser/browser_ext_lastError.js
+++ b/browser/components/extensions/test/browser/browser_ext_lastError.js
@@ -1,17 +1,17 @@
 "use strict";
 
 function* sendMessage(options) {
   function background(options) {
-    browser.runtime.sendMessage("invalid-extension-id", {}, {}, result => {
+    browser.runtime.sendMessage(result => {
       browser.test.assertEq(undefined, result, "Argument value");
       if (options.checkLastError) {
         let lastError = browser[options.checkLastError].lastError;
-        browser.test.assertEq("Invalid extension ID",
+        browser.test.assertEq("runtime.sendMessage's message argument is missing",
                               lastError && lastError.message,
                               "lastError value");
       }
       browser.test.sendMessage("done");
     });
   }
 
   let extension = ExtensionTestUtils.loadExtension({
@@ -29,27 +29,27 @@ add_task(function* testLastError() {
   // Not necessary in browser-chrome tests, but monitorConsole gripes
   // if we don't call it.
   SimpleTest.waitForExplicitFinish();
 
   // Check that we have no unexpected console messages when lastError is
   // checked.
   for (let api of ["extension", "runtime"]) {
     let waitForConsole = new Promise(resolve => {
-      SimpleTest.monitorConsole(resolve, [{message: /Invalid extension ID/, forbid: true}]);
+      SimpleTest.monitorConsole(resolve, [{message: /message argument is missing/, forbid: true}]);
     });
 
     yield sendMessage({checkLastError: api});
 
     SimpleTest.endMonitorConsole();
     yield waitForConsole;
   }
 
   // Check that we do have a console message when lastError is not checked.
   let waitForConsole = new Promise(resolve => {
-    SimpleTest.monitorConsole(resolve, [{message: /Unchecked lastError value: Error: Invalid extension ID/}]);
+    SimpleTest.monitorConsole(resolve, [{message: /Unchecked lastError value: Error: runtime.sendMessage's message argument is missing/}]);
   });
 
   yield sendMessage({});
 
   SimpleTest.endMonitorConsole();
   yield waitForConsole;
 });

--- a/toolkit/components/extensions/MessageChannel.jsm
+++ b/toolkit/components/extensions/MessageChannel.jsm
@@ -512,17 +512,21 @@ this.MessageChannel = {
     let broker = this.responseManagers.get(target);
     broker.addHandler(channelId, deferred);
 
     let cleanup = () => {
       broker.removeHandler(channelId, deferred);
     };
     deferred.promise.then(cleanup, cleanup);
 
-    target.sendAsyncMessage(MESSAGE_MESSAGE, message);
+    try {
+      target.sendAsyncMessage(MESSAGE_MESSAGE, message);
+    } catch (e) {
+      deferred.reject(e);
+    }
     return deferred.promise;
   },
 
   _callHandlers(handlers, data) {
     let responseType = data.responseType;
 
     // At least one handler is required for all response types but
     // RESPONSE_ALL.

--- a/toolkit/components/extensions/ext-runtime.js
+++ b/toolkit/components/extensions/ext-runtime.js
@@ -69,30 +69,48 @@ extensions.registerSchemaAPI("runtime", 
         let recipient = {extensionId};
 
         return context.messenger.connect(Services.cpmm, name, recipient);
       },
 
       sendMessage: function(...args) {
         let options; // eslint-disable-line no-unused-vars
         let extensionId, message, responseCallback;
-        if (args.length == 1) {
+        if (typeof args[args.length - 1] == "function") {
+          responseCallback = args.pop();
+        }
+        if (!args.length) {
+          return Promise.reject({message: "runtime.sendMessage's message argument is missing"});
+        } else if (args.length == 1) {
           message = args[0];
         } else if (args.length == 2) {
-          [message, responseCallback] = args;
+          if (typeof args[0] == "string" && args[0]) {
+            [extensionId, message] = args;
+          } else {
+            [message, options] = args;
+          }
+        } else if (args.length == 3) {
+          [extensionId, message, options] = args;
+        } else if (args.length == 4 && !responseCallback) {
+          return Promise.reject({message: "runtime.sendMessage's last argument is not a function"});
         } else {
-          [extensionId, message, options, responseCallback] = args;
+          return Promise.reject({message: "runtime.sendMessage received too many arguments"});
+        }
+
+        if (extensionId != null && typeof extensionId != "string") {
+          return Promise.reject({message: "runtime.sendMessage's extensionId argument is invalid"});
         }
+        if (options != null && typeof options != "object") {
+          return Promise.reject({message: "runtime.sendMessage's options argument is invalid"});
+        }
+        // TODO(robwu): Validate option keys and values when we support it.
+
         extensionId = extensionId || extension.id;
         let recipient = {extensionId};
 
-        if (!GlobalManager.extensionMap.has(recipient.extensionId)) {
-          return context.wrapPromise(Promise.reject({message: "Invalid extension ID"}),
-                                     responseCallback);
-        }
         return context.messenger.sendMessage(Services.cpmm, message, recipient, responseCallback);
       },
 
       connectNative(application) {
         let app = new NativeApp(extension, context, application);
         return app.portAPI();
       },
 

new file mode 100644
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_errors.js
@@ -0,0 +1,64 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(function* test_sendMessage_error() {
+  function background() {
+    let circ = {};
+    circ.circ = circ;
+    let testCases = [
+      // [arguments, expected error string],
+      [[], "runtime.sendMessage's message argument is missing"],
+      [[null, null, null, null], "runtime.sendMessage's last argument is not a function"],
+      [[null, null, 1], "runtime.sendMessage's options argument is invalid"],
+      [[1, null, null], "runtime.sendMessage's extensionId argument is invalid"],
+      [[null, null, null, null, null], "runtime.sendMessage received too many arguments"],
+
+      // Even when the parameters are accepted, we still expect an error
+      // because there is no onMessage listener.
+      [[null, null, null], "Could not establish connection. Receiving end does not exist."],
+
+      // Structural cloning doesn't work with DOM but we fall back
+      // JSON serialization, so we don't expect another error.
+      [[null, location, null], "Could not establish connection. Receiving end does not exist."],
+
+      // Structured cloning supports cyclic self-references.
+      [[null, [circ, location], null], "cyclic object value"],
+      // JSON serialization does not support cyclic references.
+      [[null, circ, null], "Could not establish connection. Receiving end does not exist."],
+      // (the last two tests shows whether sendMessage is implemented as structured cloning).
+    ];
+
+    // Repeat all tests with the undefined value instead of null.
+    for (let [args, expectedError] of testCases.slice()) {
+      args = args.map(arg => arg === null ? undefined : arg);
+      testCases.push([args, expectedError]);
+    }
+
+    function next() {
+      if (!testCases.length) {
+        browser.test.notifyPass("sendMessage parameter validation");
+        return;
+      }
+      let [args, expectedError] = testCases.shift();
+      let description = `runtime.sendMessage(${args.map(String).join(", ")})`;
+      return browser.runtime.sendMessage(...args)
+        .then(() => {
+          browser.test.fail(`Unexpectedly got no error for ${description}`);
+        }, err => {
+          browser.test.assertEq(expectedError, err.message, `expected error message for ${description}`);
+        }).then(next);
+    }
+    next();
+  }
+  let extensionData = {
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  yield extension.startup();
+
+  yield extension.awaitFinish("sendMessage parameter validation");
+
+  yield extension.unload();
+});

--- a/toolkit/components/extensions/test/xpcshell/xpcshell.ini
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell.ini
@@ -34,16 +34,17 @@ skip-if = release_build
 [test_ext_localStorage.js]
 [test_ext_management.js]
 [test_ext_manifest_content_security_policy.js]
 [test_ext_manifest_incognito.js]
 [test_ext_onmessage_removelistener.js]
 [test_ext_runtime_connect_no_receiver.js]
 [test_ext_runtime_getPlatformInfo.js]
 [test_ext_runtime_sendMessage.js]
+[test_ext_runtime_sendMessage_errors.js]
 [test_ext_runtime_sendMessage_no_receiver.js]
 [test_ext_schemas.js]
 [test_ext_schemas_api_injection.js]
 [test_ext_simple.js]
 [test_ext_storage.js]
 [test_getAPILevelForWindow.js]
 [test_locale_converter.js]
 [test_locale_data.js]