diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 66d4140289b..421b12df0db 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -23,6 +23,7 @@ Removed
 Fixed
 -----
 - loading of additional training data with the ``SkillSelector``
+- strip trailing slashes in endpoint URLs
 
 [1.0.7] - 2019-06-06
 ^^^^^^^^^^^^^^^^^^^^
diff --git a/rasa/utils/endpoints.py b/rasa/utils/endpoints.py
index 4d7ebdd4fdb..12b610ac1a3 100644
--- a/rasa/utils/endpoints.py
+++ b/rasa/utils/endpoints.py
@@ -45,7 +45,7 @@ def concat_url(base: Text, subpath: Optional[Text]) -> Text:
     `base`."""
 
     if not subpath:
-        return base
+        return base.rstrip("/")
 
     url = base
     if not base.endswith("/"):

Action server returning 404
<!-- THIS INFORMATION IS MANDATORY - YOUR ISSUE WILL BE CLOSED IF IT IS MISSING. If you don't know your Rasa Core version, use `pip list | grep rasa`. Removing the below information is allowed for FEATURE REQUESTS. --> 

**Rasa version**:1.0.1

**Python version**: 3.6.7

**Operating system** (windows, osx, ...):ubuntu 16.04

**Issue**:
I start the action_end point server .. the log is as follows:

``
rasa run actions --cors "*"
2019-05-29 14:53:05 INFO     rasa_sdk.endpoint  - Starting action endpoint server...
/home/sfrplindia1/Work/SantaFe/Raghuram/chatbots/rasa_15/lib/python3.6/site-packages/rasa_core_sdk/__init__.py:12: UserWarning: The 'rasa_core_sdk' package has been renamed. You should change your imports to use 'rasa_sdk' instead.
  UserWarning,
2019-05-29 14:53:05 INFO     rasa_sdk.executor  - Registered function for 'validate_inputs'.
2019-05-29 14:53:05 INFO     rasa_sdk.executor  - Registered function for 'action_bye'.
2019-05-29 14:53:05 INFO     rasa_sdk.executor  - Registered function for 'action_restarted'.
2019-05-29 14:53:05 INFO     rasa_sdk.executor  - Registered function for 'action_slot_reset'.
2019-05-29 14:53:05 INFO     rasa_sdk.executor  - Registered function for 'appointment_form'.
2019-05-29 14:53:05 INFO     rasa_sdk.endpoint  - Action endpoint is up and running. on ('0.0.0.0', 5055)
```





**Content of configuration file (config.yml)**:
```yml
language: en

pipeline:
  - name: WhitespaceTokenizer
  - name: CRFEntityExtractor
  - name: EntitySynonymMapper
  - name: CountVectorsFeaturizer
    token_pattern: (?u)\b\w+\b
  - name: EmbeddingIntentClassifier
  - name: DucklingHTTPExtractor
    url: http://localhost:8000
    dimensions:
      - time

policies:
  - name: KerasPolicy
    epochs: 100
    max_history: 5
  - name: MemoizationPolicy
    max_history: 5
  - name: FormPolicy 

```

**Content of domain file (domain.yml)** (if used & relevant):
```yaml
actions:
- utter_greet
- utter_bye
- utter_schedule_appointment
- utter_affirmative
- utter_incorrect_dept
- action_bye
- action_slot_reset
- action_split_date_time
- validate_inputs
- utter_ask_dept
- utter_ask_date
- utter_ask_name
- utter_incorrect_time


slots:
    dept:
      type: text
    date_slot:
      type: unfeaturized
    time_slot:
      type: unfeaturized
    doc_slot:
      type: unfeaturized
    time:
      type: unfeaturized
    name:
      type : unfeaturized
    requested_slot:
      type: unfeaturized  

intents:
- schedule_appointment:
    use_entities : True
- greet
- bye
- affirmative
 
entities:
- dept
- time
- name
templates:
    utter_greet:
    - 'Hello there ! How can I help?'
    utter_bye:
    - 'Bye! Take care'
    utter_ask_dept:
    - 'With which speciality?'
    utter_ask_date:
    - 'On which date would you like to schedule the appointment?'
    utter_ask_time:
    - 'At what time would you like to schedule the appointment?'
    utter_ask_name:
    - 'In whose name would you like to schedule the appointment?'
    utter_incorrect_dept:
    - 'Sorry this speciality does not exist. You will have to enter the speciality again.'
    utter_incorrect_time:
    - 'Sorry! No doctor is available at date and time that you have entered. Please enter the date and time again'
    utter_incorrect_date:
    - 'Sorry the date you have entered is incorrect. Please enter the date and time again'    
    utter_schedule_appointment:
    - 'Shall I confirm your appointment with {doc_slot} in the {dept} department on {date_slot} in the {time_slot}?'
    utter_affirmative:
    - 'Thank you! I am confirming your appointment with {doc_slot} in the {dept} department on {date_slot} in the {time_slot}'
    utter_finish:
    - 'thank you for entering the details'   
    
forms:
- appointment_form


```
My endpoints.yml

```
action_endpoint:
  url: "http://localhost:5055/webhook/"
```

This is the ValidateInputs function
```
class ValidateInputs(Action):
    def name(self):
        return 'validate_inputs'

    .........
```
During interactive learning, when i try to run the validate_inputs actions, i get the following error:
```
What is the next action of the bot?  0.00 validate_inputs                                                                                                                                                       
Thanks! The bot will now run validate_inputs.

2019-05-29 14:53:46 DEBUG    rasa.core.tracker_store  - Recreating tracker for id '5cf18e01f02242af875ebc33d557cda0'
2019-05-29 14:53:46 DEBUG    rasa.core.tracker_store  - Recreating tracker for id '5cf18e01f02242af875ebc33d557cda0'
2019-05-29 14:53:46 DEBUG    rasa.core.actions.action  - Calling action endpoint to run action 'validate_inputs'.
2019-05-29 14:53:46 ERROR    rasa.core.processor  - Encountered an exception while running action 'validate_inputs'. Bot will continue, but the actions events are lost. Make sure to fix the exception in your custom code.
2019-05-29 14:53:46 DEBUG    rasa.core.processor  - Failed to execute custom action.
Traceback (most recent call last):
  File "/home/sfrplindia1/Work/SantaFe/Raghuram/chatbots/rasa_15/lib/python3.6/site-packages/rasa/core/actions/action.py", line 410, in run
    json=json_body, method="post", timeout=DEFAULT_REQUEST_TIMEOUT
  File "/usr/lib/python3.6/asyncio/coroutines.py", line 110, in __next__
    return self.gen.send(None)
  File "/home/sfrplindia1/Work/SantaFe/Raghuram/chatbots/rasa_15/lib/python3.6/site-packages/rasa/utils/endpoints.py", line 140, in request
    resp.status, resp.reason, await resp.content.read()
rasa.utils.endpoints.ClientResponseError: 404, NOT FOUND, body='b'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n<title>404 Not Found</title>\n<h1>Not Found</h1>\n<p>The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.</p>\n''

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/sfrplindia1/Work/SantaFe/Raghuram/chatbots/rasa_15/lib/python3.6/site-packages/rasa/core/processor.py", line 431, in _run_action
    events = await action.run(output_channel, nlg, tracker, self.domain)
  File "/usr/lib/python3.6/asyncio/coroutines.py", line 110, in __next__
    return self.gen.send(None)
  File "/home/sfrplindia1/Work/SantaFe/Raghuram/chatbots/rasa_15/lib/python3.6/site-packages/rasa/core/actions/action.py", line 432, in run
    raise Exception("Failed to execute custom action.") from e
Exception: Failed to execute custom action.
2019-05-29 14:53:46 DEBUG    rasa.core.processor  - Action 'validate_inputs' ended with events '[]'
```
The action server returns
```
127.0.0.1 - - [2019-05-29 14:53:46] "POST /webhook/ HTTP/1.1" 404 373 0.001859

```
Interestingly the action server did run utter_greet which comes before validate_inputs in the sequence
```

 #    Bot                                                                                                                                                            You        
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 1    action_listen                                                                                                                                                             
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 2                                                                                                                                                                           hi 
                                                                                                                                                             intent: greet 0.89 
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
 3    utter_greet 1.00                                                                                                                                                          
      Hello there ! How can I help?                                                                                                                                             
      action_listen 1.00                                                                                                                                                        
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
                  

```
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 71343f666cb..fe6cf813c28 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,5 +1,6 @@
+import pytest
 from aioresponses import aioresponses
-from rasa.utils.endpoints import EndpointConfig
+from rasa.utils.endpoints import EndpointConfig, concat_url
 from tests.utilities import latest_request, json_of_latest_request
 from rasa.utils.common import sort_list_of_dicts_by_first_key
 
@@ -61,3 +62,18 @@ def test_sort_dicts_by_keys():
     actual = sort_list_of_dicts_by_first_key(test_data)
 
     assert actual == expected
+
+
+@pytest.mark.parametrize(
+    "base, subpath, expected_result",
+    [
+        ("https://example.com", None, "https://example.com"),
+        ("https://example.com/test", None, "https://example.com/test"),
+        ("https://example.com/", None, "https://example.com"),
+        ("https://example.com//", None, "https://example.com"),
+        ("https://example.com/", "test", "https://example.com/test"),
+        ("https://example.com/", "test/", "https://example.com/test/"),
+    ],
+)
+def test_concat_url(base, subpath, expected_result):
+    assert concat_url(base, subpath) == expected_result

pip install -e .[dev]
parse_log_pytest
requirements.txt
pytest pytest-cov pytest-localserver pytest-sanic responses freezegun nbsphinx aioresponses moto
apt-get update apt-get install -y gcc
3.6
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
absl-py==1.4.0
aiofiles==0.8.0
aiohttp==3.5.4
aioresponses==0.7.6
alabaster==0.7.13
anyio==3.6.2
APScheduler==3.6.0
astor==0.8.1
async-generator==1.10
async-timeout==3.0.1
attrs==22.2.0
Babel==2.11.0
backports.zoneinfo==0.2.1
bleach==4.1.0
boto3==1.15.18
botocore==1.18.18
cached-property==1.5.2
certifi==2021.5.30
cffi==1.15.1
chardet==3.0.4
charset-normalizer==3.0.1
click==7.1.2
colorclass==2.2.0
coloredlogs==10.0
colorhash==1.0.2
ConfigArgParse==0.15.2
contextvars==2.4
coverage==6.2
cryptography==40.0.2
cycler==0.11.0
dataclasses==0.8
decorator==5.1.1
defusedxml==0.7.1
docopt==0.6.2
docutils==0.15.2
entrypoints==0.4
fakeredis==1.0.3
fbmessenger==6.0.0
Flask==1.1.4
Flask-Cors==3.0.10
freezegun==1.2.2
future==0.18.3
gast==0.6.0
gevent==1.4.0
greenlet==2.0.2
grpcio==1.48.2
h11==0.12.0
h5py==3.1.0
httpcore==0.14.7
httptools==0.6.0
httpx==0.22.0
humanfriendly==10.0
idna==2.8
idna-ssl==1.1.0
imagesize==1.4.1
immutables==0.19
importlib-metadata==4.8.3
importlib-resources==5.4.0
iniconfig==1.1.1
ipython-genutils==0.2.0
itsdangerous==1.1.0
Jinja2==2.11.3
jmespath==0.10.0
jsonpickle==1.1
jsonschema==2.6.0
jupyter-client==7.1.2
jupyter-core==4.9.2
jupyterlab-pygments==0.1.2
kafka-python==1.4.6
Keras-Applications==1.0.8
Keras-Preprocessing==1.1.2
kiwisolver==1.3.1
Markdown==3.3.7
MarkupSafe==2.0.1
matplotlib==3.0.3
mattermostwrapper==2.1
mistune==0.8.4
mock==5.2.0
moto==4.0.13
multidict==4.7.6
nbclient==0.5.9
nbconvert==6.0.7
nbformat==5.1.3
nbsphinx==0.8.8
nest-asyncio==1.6.0
networkx==2.3
numpy==1.16.3
packaging==19.2
pandocfilters==1.5.1
pika==1.0.1
pluggy==1.0.0
prompt-toolkit==2.0.10
protobuf==3.19.6
psycopg2-binary==2.8.2
py==1.11.0
pycparser==2.21
pydot==1.4.1
Pygments==2.14.0
PyJWT==2.4.0
pykwalify==1.7.0
pymongo==3.8.0
pyparsing==3.1.4
PySocks==1.7.1
pytest==7.0.1
pytest-cov==4.0.0
pytest-localserver==0.9.0.post0
pytest-sanic==1.7.1
python-crfsuite==0.9.10
python-dateutil==2.8.0
python-engineio==4.11.2
python-socketio==4.0.1
python-telegram-bot==11.1.0
pytz==2019.1
pytz-deprecation-shim==0.1.0.post0
PyYAML==6.0.1
pyzmq==25.1.2
questionary==1.1.1
-e git+https://github.com/RasaHQ/rasa.git@e7c8420822e2fbf5e0c1b085f0f2187ed777ed24#egg=rasa
rasa-sdk==1.0.0
redis==3.2.1
requests==2.22.0
requests-toolbelt==1.0.0
responses==0.17.0
rfc3986==1.5.0
rocketchat-API==0.6.31
ruamel.yaml==0.15.94
s3transfer==0.3.7
sanic==19.3.1
Sanic-Cors==0.9.8
sanic-jwt==1.3.1
Sanic-Plugins-Framework==0.9.5
scikit-learn==0.20.2
scipy==1.2.1
simple-websocket==1.1.0
simplejson==3.16.0
six==1.17.0
sklearn-crfsuite==0.3.6
slackclient==1.3.1
sniffio==1.2.0
snowballstemmer==2.2.0
sortedcontainers==2.4.0
Sphinx==5.3.0
sphinxcontrib-applehelp==1.0.2
sphinxcontrib-devhelp==1.0.2
sphinxcontrib-htmlhelp==2.0.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==1.0.3
sphinxcontrib-serializinghtml==1.1.5
SQLAlchemy==1.3.24
tabulate==0.8.10
tensorboard==1.13.1
tensorflow==1.13.1
tensorflow-estimator==1.13.0
termcolor==1.1.0
terminaltables==3.1.0
testpath==0.6.0
tomli==1.2.3
tornado==6.1
tqdm==4.31.0
traitlets==4.3.3
twilio==6.26.3
typing_extensions==4.1.1
tzdata==2025.2
tzlocal==4.2
ujson==4.3.0
urllib3==1.24.3
uvloop==0.14.0
wcwidth==0.2.13
webencodings==0.5.1
webexteamssdk==1.1.1
websocket-client==0.54.0
websockets==6.0
Werkzeug==1.0.1
wsproto==1.0.0
xmltodict==0.14.2
yarl==1.7.2
zipp==3.6.0

name: rasa
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=21.2.2=py36h06a4308_0
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - absl-py==1.4.0
      - aiofiles==0.8.0
      - aiohttp==3.5.4
      - aioresponses==0.7.6
      - alabaster==0.7.13
      - anyio==3.6.2
      - apscheduler==3.6.0
      - astor==0.8.1
      - async-generator==1.10
      - async-timeout==3.0.1
      - attrs==22.2.0
      - babel==2.11.0
      - backports-zoneinfo==0.2.1
      - bleach==4.1.0
      - boto3==1.15.18
      - botocore==1.18.18
      - cached-property==1.5.2
      - cffi==1.15.1
      - chardet==3.0.4
      - charset-normalizer==3.0.1
      - click==7.1.2
      - colorclass==2.2.0
      - coloredlogs==10.0
      - colorhash==1.0.2
      - configargparse==0.15.2
      - contextvars==2.4
      - coverage==6.2
      - cryptography==40.0.2
      - cycler==0.11.0
      - dataclasses==0.8
      - decorator==5.1.1
      - defusedxml==0.7.1
      - docopt==0.6.2
      - docutils==0.15.2
      - entrypoints==0.4
      - fakeredis==1.0.3
      - fbmessenger==6.0.0
      - flask==1.1.4
      - flask-cors==3.0.10
      - freezegun==1.2.2
      - future==0.18.3
      - gast==0.6.0
      - gevent==1.4.0
      - greenlet==2.0.2
      - grpcio==1.48.2
      - h11==0.12.0
      - h5py==3.1.0
      - httpcore==0.14.7
      - httptools==0.6.0
      - httpx==0.22.0
      - humanfriendly==10.0
      - idna==2.8
      - idna-ssl==1.1.0
      - imagesize==1.4.1
      - immutables==0.19
      - importlib-metadata==4.8.3
      - importlib-resources==5.4.0
      - iniconfig==1.1.1
      - ipython-genutils==0.2.0
      - itsdangerous==1.1.0
      - jinja2==2.11.3
      - jmespath==0.10.0
      - jsonpickle==1.1
      - jsonschema==2.6.0
      - jupyter-client==7.1.2
      - jupyter-core==4.9.2
      - jupyterlab-pygments==0.1.2
      - kafka-python==1.4.6
      - keras-applications==1.0.8
      - keras-preprocessing==1.1.2
      - kiwisolver==1.3.1
      - markdown==3.3.7
      - markupsafe==2.0.1
      - matplotlib==3.0.3
      - mattermostwrapper==2.1
      - mistune==0.8.4
      - mock==5.2.0
      - moto==4.0.13
      - multidict==4.7.6
      - nbclient==0.5.9
      - nbconvert==6.0.7
      - nbformat==5.1.3
      - nbsphinx==0.8.8
      - nest-asyncio==1.6.0
      - networkx==2.3
      - numpy==1.16.3
      - packaging==19.2
      - pandocfilters==1.5.1
      - pika==1.0.1
      - pluggy==1.0.0
      - prompt-toolkit==2.0.10
      - protobuf==3.19.6
      - psycopg2-binary==2.8.2
      - py==1.11.0
      - pycparser==2.21
      - pydot==1.4.1
      - pygments==2.14.0
      - pyjwt==2.4.0
      - pykwalify==1.7.0
      - pymongo==3.8.0
      - pyparsing==3.1.4
      - pysocks==1.7.1
      - pytest==7.0.1
      - pytest-cov==4.0.0
      - pytest-localserver==0.9.0.post0
      - pytest-sanic==1.7.1
      - python-crfsuite==0.9.10
      - python-dateutil==2.8.0
      - python-engineio==4.11.2
      - python-socketio==4.0.1
      - python-telegram-bot==11.1.0
      - pytz==2019.1
      - pytz-deprecation-shim==0.1.0.post0
      - pyyaml==6.0.1
      - pyzmq==25.1.2
      - questionary==1.1.1
      - rasa-sdk==1.0.0
      - redis==3.2.1
      - requests==2.22.0
      - requests-toolbelt==1.0.0
      - responses==0.17.0
      - rfc3986==1.5.0
      - rocketchat-api==0.6.31
      - ruamel-yaml==0.15.94
      - s3transfer==0.3.7
      - sanic==19.3.1
      - sanic-cors==0.9.8
      - sanic-jwt==1.3.1
      - sanic-plugins-framework==0.9.5
      - scikit-learn==0.20.2
      - scipy==1.2.1
      - simple-websocket==1.1.0
      - simplejson==3.16.0
      - six==1.17.0
      - sklearn-crfsuite==0.3.6
      - slackclient==1.3.1
      - sniffio==1.2.0
      - snowballstemmer==2.2.0
      - sortedcontainers==2.4.0
      - sphinx==5.3.0
      - sphinxcontrib-applehelp==1.0.2
      - sphinxcontrib-devhelp==1.0.2
      - sphinxcontrib-htmlhelp==2.0.0
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==1.0.3
      - sphinxcontrib-serializinghtml==1.1.5
      - sqlalchemy==1.3.24
      - tabulate==0.8.10
      - tensorboard==1.13.1
      - tensorflow==1.13.1
      - tensorflow-estimator==1.13.0
      - termcolor==1.1.0
      - terminaltables==3.1.0
      - testpath==0.6.0
      - tomli==1.2.3
      - tornado==6.1
      - tqdm==4.31.0
      - traitlets==4.3.3
      - twilio==6.26.3
      - typing-extensions==4.1.1
      - tzdata==2025.2
      - tzlocal==4.2
      - ujson==4.3.0
      - urllib3==1.24.3
      - uvloop==0.14.0
      - wcwidth==0.2.13
      - webencodings==0.5.1
      - webexteamssdk==1.1.1
      - websocket-client==0.54.0
      - websockets==6.0
      - werkzeug==1.0.1
      - wsproto==1.0.0
      - xmltodict==0.14.2
      - yarl==1.7.2
      - zipp==3.6.0
prefix: /opt/conda/envs/rasa

tests/test_utils.py::test_concat_url[https://example.com/-None-https://example.com] tests/test_utils.py::test_concat_url[https://example.com//-None-https://example.com]
tests/test_utils.py::test_endpoint_config tests/test_utils.py::test_sort_dicts_by_keys tests/test_utils.py::test_concat_url[https://example.com-None-https://example.com] tests/test_utils.py::test_concat_url[https://example.com/test-None-https://example.com/test] tests/test_utils.py::test_concat_url[https://example.com/-test-https://example.com/test] tests/test_utils.py::test_concat_url[https://example.com/-test/-https://example.com/test/]
CHANGELOG.rst rasa/utils/endpoints.py
CHANGELOG.rst rasa/utils/endpoints.py