--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/executors/executorwebdriver.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/executors/executorwebdriver.py
@@ -1,11 +1,12 @@
 import json
 import os
 import socket
+import sys
 import threading
 import time
 import traceback
 import urlparse
 import uuid
 
 from .base import (CallbackHandler,
                    RefTestExecutor,
@@ -227,20 +228,24 @@ class WebDriverProtocol(Protocol):
         capabilities = {"alwaysMatch": self.capabilities}
         self.webdriver = client.Session(host, port, capabilities=capabilities)
         self.webdriver.start()
 
 
     def teardown(self):
         self.logger.debug("Hanging up on WebDriver session")
         try:
-            self.webdriver.quit()
-        except Exception:
-            pass
-        del self.webdriver
+            self.webdriver.end()
+        except Exception as e:
+            message = str(getattr(e, "message", ""))
+            if message:
+                message += "\n"
+            message += traceback.format_exc(e)
+            self.logger.debug(message)
+        self.webdriver = None
 
     def is_alive(self):
         try:
             # Get a simple property over the connection
             self.webdriver.window_handle
         except (socket.timeout, client.UnknownErrorException):
             return False
         return True
@@ -272,17 +277,20 @@ class WebDriverRun(object):
 
         flag = self.result_flag.wait(timeout + 2 * extra_timeout)
         if self.result is None:
             if flag:
                 # flag is True unless we timeout; this *shouldn't* happen, but
                 # it can if self._run fails to set self.result due to raising
                 self.result = False, ("INTERNAL-ERROR", "self._run didn't set a result")
             else:
-                self.result = False, ("EXTERNAL-TIMEOUT", None)
+                message = "Waiting on browser:\n"
+                # get a traceback for the current stack of the executor thread
+                message += "".join(traceback.format_stack(sys._current_frames()[executor.ident]))
+                self.result = False, ("EXTERNAL-TIMEOUT", message)
 
         return self.result
 
     def _run(self):
         try:
             self.result = True, self.func(self.protocol, self.url, self.timeout)
         except (client.TimeoutException, client.ScriptTimeoutException):
             self.result = False, ("EXTERNAL-TIMEOUT", None)

--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/webdriver_server.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/webdriver_server.py
@@ -76,16 +76,17 @@ class WebDriverServer(object):
                 "WebDriver was not accessible "
                 "within the timeout:\n%s" % traceback.format_exc())
             raise
 
         if block:
             self._proc.wait()
 
     def stop(self, force=False):
+        self.logger.debug("Stopping WebDriver")
         if self.is_alive:
             return self._proc.kill()
         return not self.is_alive
 
     @property
     def is_alive(self):
         return hasattr(self._proc, "proc") and self._proc.poll() is None