diff --git a/.circleci/config.yml b/.circleci/config.yml
index a817962452..176d3817c6 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -385,7 +385,7 @@ jobs:
           PERCY_ENABLE: 1
           PERCY_PARALLEL_TOTAL: -1
 
-    parallelism: 4
+    parallelism: 5
 
     steps:
       - checkout:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 29e44e5b62..a9dc025d4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 All notable changes to `dash` will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
+## [2.3.1] - 2022-03-29
+
+### Fixed
+
+- [#1963](https://github.com/plotly/dash/pull/1963) Fix [#1780](https://github.com/plotly/dash/issues/1780) flask shutdown deprecation warning when running dashduo threaded tests.
+- [#1995](https://github.com/plotly/dash/pull/1995) Fix [#1992](https://github.com/plotly/dash/issues/1992) ImportError: cannot import name 'get_current_traceback' from 'werkzeug.debug.tbtools'.
+
 ## [2.3.0] - 2022-03-13
 
 ### Added
diff --git a/components/dash-table/tests/selenium/test_sizing.py b/components/dash-table/tests/selenium/test_sizing.py
index 707678aa41..d2f743e7e4 100644
--- a/components/dash-table/tests/selenium/test_sizing.py
+++ b/components/dash-table/tests/selenium/test_sizing.py
@@ -1,12 +1,7 @@
 import dash
-import pytest
 
 from utils import (
-    basic_modes,
     get_props,
-    generate_mock_data,
-    generate_markdown_mock_data,
-    generate_mixed_markdown_data,
 )
 
 from dash.dependencies import Input, Output
@@ -294,12 +289,7 @@ def test_szng002_percentages_result_in_same_widths(test):
     assert test.get_log_errors() == []
 
 
-@pytest.mark.parametrize("props", basic_modes)
-@pytest.mark.parametrize(
-    "data_fn",
-    [generate_mock_data, generate_markdown_mock_data, generate_mixed_markdown_data],
-)
-def test_szng004_on_focus(test, props, data_fn):
+def on_focus(test, props, data_fn):
     app = dash.Dash(__name__)
 
     baseProps1 = get_props(data_fn=data_fn)
diff --git a/components/dash-table/tests/selenium/test_sizing_x.py b/components/dash-table/tests/selenium/test_sizing_x.py
new file mode 100644
index 0000000000..51dfefc046
--- /dev/null
+++ b/components/dash-table/tests/selenium/test_sizing_x.py
@@ -0,0 +1,13 @@
+import pytest
+
+from test_sizing import on_focus
+
+from utils import (
+    basic_modes,
+    generate_mock_data,
+)
+
+
+@pytest.mark.parametrize("props", basic_modes)
+def test_szng004_on_focus(test, props):
+    on_focus(test, props, generate_mock_data)
diff --git a/components/dash-table/tests/selenium/test_sizing_y.py b/components/dash-table/tests/selenium/test_sizing_y.py
new file mode 100644
index 0000000000..7a2344cab0
--- /dev/null
+++ b/components/dash-table/tests/selenium/test_sizing_y.py
@@ -0,0 +1,13 @@
+import pytest
+
+from test_sizing import on_focus
+
+from utils import (
+    basic_modes,
+    generate_markdown_mock_data,
+)
+
+
+@pytest.mark.parametrize("props", basic_modes)
+def test_szng005_on_focus(test, props):
+    on_focus(test, props, generate_markdown_mock_data)
diff --git a/components/dash-table/tests/selenium/test_sizing_z.py b/components/dash-table/tests/selenium/test_sizing_z.py
new file mode 100644
index 0000000000..004ad015dd
--- /dev/null
+++ b/components/dash-table/tests/selenium/test_sizing_z.py
@@ -0,0 +1,13 @@
+import pytest
+
+from test_sizing import on_focus
+
+from utils import (
+    basic_modes,
+    generate_mixed_markdown_data,
+)
+
+
+@pytest.mark.parametrize("props", basic_modes)
+def test_szng006_on_focus(test, props):
+    on_focus(test, props, generate_mixed_markdown_data)
diff --git a/dash/_dash_renderer.py b/dash/_dash_renderer.py
index b7bdcfbccf..ce978ec74e 100644
--- a/dash/_dash_renderer.py
+++ b/dash/_dash_renderer.py
@@ -1,4 +1,4 @@
-__version__ = "1.11.3"
+__version__ = "1.11.4"
 
 _js_dist_dependencies = [
     {
@@ -39,7 +39,7 @@
     {
         "relative_package_path": "dash-renderer/build/dash_renderer.min.js",
         "dev_package_path": "dash-renderer/build/dash_renderer.dev.js",
-        "external_url": "https://unpkg.com/dash-renderer@1.11.3"
+        "external_url": "https://unpkg.com/dash-renderer@1.11.4"
         "/build/dash_renderer.min.js",
         "namespace": "dash",
     },
diff --git a/dash/_utils.py b/dash/_utils.py
index 31de7e88cb..83b2895554 100644
--- a/dash/_utils.py
+++ b/dash/_utils.py
@@ -8,6 +8,8 @@
 import logging
 import io
 import json
+import secrets
+import string
 from functools import wraps
 
 logger = logging.getLogger()
@@ -206,3 +208,9 @@ def _wrapper(*args, **kwargs):
         return _wrapper
 
     return wrapper
+
+
+def gen_salt(chars):
+    return "".join(
+        secrets.choice(string.ascii_letters + string.digits) for _ in range(chars)
+    )
diff --git a/dash/dash-renderer/package-lock.json b/dash/dash-renderer/package-lock.json
index 07b3ed0b5b..b9e768168f 100644
--- a/dash/dash-renderer/package-lock.json
+++ b/dash/dash-renderer/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "dash-renderer",
-  "version": "1.11.3",
+  "version": "1.11.4",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "dash-renderer",
-      "version": "1.11.3",
+      "version": "1.11.4",
       "license": "MIT",
       "dependencies": {
         "@babel/polyfill": "^7.12.1",
diff --git a/dash/dash-renderer/package.json b/dash/dash-renderer/package.json
index e03100240e..57171862c6 100644
--- a/dash/dash-renderer/package.json
+++ b/dash/dash-renderer/package.json
@@ -1,6 +1,6 @@
 {
   "name": "dash-renderer",
-  "version": "1.11.3",
+  "version": "1.11.4",
   "description": "render dash components in react",
   "main": "build/dash_renderer.min.js",
   "scripts": {
diff --git a/dash/dash-renderer/src/components/error/FrontEnd/FrontEndError.react.js b/dash/dash-renderer/src/components/error/FrontEnd/FrontEndError.react.js
index 5703add4db..49939ea1de 100644
--- a/dash/dash-renderer/src/components/error/FrontEnd/FrontEndError.react.js
+++ b/dash/dash-renderer/src/components/error/FrontEnd/FrontEndError.react.js
@@ -110,7 +110,7 @@ function UnconnectedErrorContent({error, base}) {
             )}
             {/* Backend Error */}
             {typeof error.html !== 'string' ? null : error.html.indexOf(
-                  '<!DOCTYPE HTML'
+                  '<!DOCTYPE'
               ) === 0 ? (
                 <div className='dash-be-error__st'>
                     <div className='dash-backend-error'>
diff --git a/dash/dash.py b/dash/dash.py
index c0b6cb410d..cc04b48b10 100644
--- a/dash/dash.py
+++ b/dash/dash.py
@@ -11,11 +11,12 @@
 import mimetypes
 import hashlib
 import base64
+import traceback
 from urllib.parse import urlparse
 
 import flask
 from flask_compress import Compress
-from werkzeug.debug.tbtools import get_current_traceback
+
 from pkg_resources import get_distribution, parse_version
 from dash import dcc
 from dash import html
@@ -48,6 +49,7 @@
     patch_collections_abc,
     split_callback_id,
     to_json,
+    gen_salt,
 )
 from . import _callback
 from . import _get_paths
@@ -102,6 +104,42 @@
 _re_renderer_scripts_id = 'id="_dash-renderer', "new DashRenderer"
 
 
+def _get_traceback(secret, error: Exception):
+
+    try:
+        # pylint: disable=import-outside-toplevel
+        from werkzeug.debug import tbtools
+    except ImportError:
+        tbtools = None
+
+    def _get_skip(text, divider=2):
+        skip = 0
+        for i, line in enumerate(text):
+            if "%% callback invoked %%" in line:
+                skip = int((i + 1) / divider)
+                break
+        return skip
+
+    # werkzeug<2.1.0
+    if hasattr(tbtools, "get_current_traceback"):
+        tb = tbtools.get_current_traceback()
+        skip = _get_skip(tb.plaintext.splitlines())
+        return tbtools.get_current_traceback(skip=skip).render_full()
+
+    if hasattr(tbtools, "DebugTraceback"):
+        tb = tbtools.DebugTraceback(error)  # pylint: disable=no-member
+        skip = _get_skip(tb.render_traceback_text().splitlines())
+
+        # pylint: disable=no-member
+        return tbtools.DebugTraceback(error, skip=skip).render_debugger_html(
+            True, secret, True
+        )
+
+    tb = traceback.format_exception(type(error), error, error.__traceback__)
+    skip = _get_skip(tb, 1)
+    return tb[0] + "".join(tb[skip:])
+
+
 class _NoUpdate:
     # pylint: disable=too-few-public-methods
     pass
@@ -1756,19 +1794,16 @@ def enable_dev_tools(
 
         if debug and dev_tools.prune_errors:
 
+            secret = gen_salt(20)
+
             @self.server.errorhandler(Exception)
-            def _wrap_errors(_):
+            def _wrap_errors(error):
                 # find the callback invocation, if the error is from a callback
                 # and skip the traceback up to that point
                 # if the error didn't come from inside a callback, we won't
                 # skip anything.
-                tb = get_current_traceback()
-                skip = 0
-                for i, line in enumerate(tb.plaintext.splitlines()):
-                    if "%% callback invoked %%" in line:
-                        skip = int((i + 1) / 2)
-                        break
-                return get_current_traceback(skip=skip).render_full(), 500
+                tb = _get_traceback(secret, error)
+                return tb, 500
 
         if debug and dev_tools.ui:
 
diff --git a/dash/testing/application_runners.py b/dash/testing/application_runners.py
index 87a7b9cb28..2a79d0373e 100644
--- a/dash/testing/application_runners.py
+++ b/dash/testing/application_runners.py
@@ -7,9 +7,9 @@
 import subprocess
 import logging
 import inspect
+import ctypes
 
 import runpy
-import flask
 import requests
 
 from dash.testing.errors import NoAppFoundError, TestingTimeoutError, ServerCloseError
@@ -102,6 +102,26 @@ def tmp_app_path(self):
         return self._tmp_app_path
 
 
+class StoppableThread(threading.Thread):
+    def get_id(self):  # pylint: disable=R1710
+        if hasattr(self, "_thread_id"):
+            return self._thread_id
+        for thread_id, thread in threading._active.items():  # pylint: disable=W0212
+            if thread is self:
+                return thread_id
+
+    def kill(self):
+        thread_id = self.get_id()
+        res = ctypes.pythonapi.PyThreadState_SetAsyncExc(
+            ctypes.c_long(thread_id), ctypes.py_object(SystemExit)
+        )
+        if res == 0:
+            raise ValueError(f"Invalid thread id: {thread_id}")
+        if res > 1:
+            ctypes.pythonapi.PyThreadState_SetAsyncExc(ctypes.c_long(thread_id), None)
+            raise SystemExit("Stopping thread failure")
+
+
 class ThreadedRunner(BaseDashRunner):
     """Runs a dash application in a thread.
 
@@ -110,25 +130,14 @@ class ThreadedRunner(BaseDashRunner):
 
     def __init__(self, keep_open=False, stop_timeout=3):
         super().__init__(keep_open=keep_open, stop_timeout=stop_timeout)
-        self.stop_route = "/_stop-{}".format(uuid.uuid4().hex)
         self.thread = None
 
-    @staticmethod
-    def _stop_server():
-        # https://werkzeug.palletsprojects.com/en/0.15.x/serving/#shutting-down-the-server
-        stopper = flask.request.environ.get("werkzeug.server.shutdown")
-        if stopper is None:
-            raise RuntimeError("Not running with the Werkzeug Server")
-        stopper()
-        return "Flask server is shutting down"
-
     # pylint: disable=arguments-differ
     def start(self, app, **kwargs):
         """Start the app server in threading flavor."""
-        app.server.add_url_rule(self.stop_route, self.stop_route, self._stop_server)
 
         def _handle_error():
-            self._stop_server()
+            self.stop()
 
         app.server.errorhandler(500)(_handle_error)
 
@@ -139,9 +148,13 @@ def run():
                 kwargs["port"] = self.port
             else:
                 self.port = kwargs["port"]
-            app.run_server(threaded=True, **kwargs)
 
-        self.thread = threading.Thread(target=run)
+            try:
+                app.run_server(threaded=True, **kwargs)
+            except SystemExit:
+                logger.info("Server stopped")
+
+        self.thread = StoppableThread(target=run)
         self.thread.daemon = True
         try:
             self.thread.start()
@@ -155,7 +168,8 @@ def run():
         wait.until(lambda: self.accessible(self.url), timeout=1)
 
     def stop(self):
-        requests.get("{}{}".format(self.url, self.stop_route))
+        self.thread.kill()
+        self.thread.join()
         wait.until_not(self.thread.is_alive, self.stop_timeout)
 
 
diff --git a/dash/version.py b/dash/version.py
index 55e4709070..3a5935a2d0 100644
--- a/dash/version.py
+++ b/dash/version.py
@@ -1 +1 @@
-__version__ = "2.3.0"
+__version__ = "2.3.1"
diff --git a/requires-ci.txt b/requires-ci.txt
index dbeb8476c0..6106e2fafb 100644
--- a/requires-ci.txt
+++ b/requires-ci.txt
@@ -1,5 +1,6 @@
 # Dependencies used by CI on github.com/plotly/dash
 black==21.6b0
+click<8.1
 dash-flow-example==0.0.5
 dash-dangerously-set-inner-html
 flake8==3.9.2