diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 5058ae39943..790785a1f48 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -33,6 +33,8 @@ Fixed
 -----
 - all temporal model files are now deleted after stopping the Rasa server
 - ``rasa shell nlu`` now outputs unicode characters instead of ``\uxxxx`` codes
+- ``x in AnySlotDict`` is now ``True`` for any ``x``, which fixes empty slot warnings in
+  interactive learning
 - ``rasa train`` now also includes NLU files in other formats than the Rasa format
 
 
diff --git a/rasa/core/trackers.py b/rasa/core/trackers.py
index 054f15bec22..c2061110e06 100644
--- a/rasa/core/trackers.py
+++ b/rasa/core/trackers.py
@@ -53,6 +53,9 @@ class AnySlotDict(dict):
         value = self[key] = Slot(key)
         return value
 
+    def __contains__(self, key):
+        return True
+
 
 class DialogueStateTracker(object):
     """Maintains the state of a conversation.

 Tried to set non existent slot 'count_list'. Make sure you added all your slots to your domain file.
<!-- THIS INFORMATION IS MANDATORY - YOUR ISSUE WILL BE CLOSED IF IT IS MISSING. If you don't know your Rasa version, use `rasa --version`. 
Please format any code or console output with three ticks ``` above and below.
If you are asking a usage question (e.g. "How do I do xyz") please post your question on https://forum.rasa.com instead -->

**Rasa version**: 1.1.3

**Rasa X version** (if used & relevant):Not using

**Python version**: 3.6.8

**Operating system** (windows, osx, ...): Windows 10

**Issue**: When i tried to use interactive learning getting this error though i mentioned all the slots in domain file.. It was working well earlier in rasa==1.0.7 version.



**Error (including full traceback)**:
```
2019-06-17 19:35:24 DEBUG    rasa.core.tracker_store  - Recreating tracker for id 'ca2c5d2b07f140bb90668586f1c28b10'
2019-06-17 19:35:24 DEBUG    rasa.core.processor  - Received user message 'list all impacted cis' with intent '{'name': 'ci_info', 'confidence': 0.9596539735794067}' and entities '[{'start': 0, 'end': 4, 'value': 'List', 'entity': 'count_list', 'confidence': 0.9737233844587407, 'extractor': 'CRFEntityExtractor', 'processors': ['EntitySynonymMapper']}, {'start': 9, 'end': 17, 'value': 'Impacted', 'entity': 'impa_noimpa', 'confidence': 0.9975736855043231, 'extractor': 'CRFEntityExtractor', 'processors': ['EntitySynonymMapper']}]'
2019-06-17 19:35:24 DEBUG    rasa.core.processor  - Current slot values:
        count_list: List
        filter1: None
        impa_noimpa: Impacted
        item_text: None
        item_value: None
        open_close: None
2019-06-17 19:35:24 DEBUG    rasa.core.processor  - Logged UserUtterance - tracker now has 4 events
2019-06-17 19:35:25 DEBUG    rasa.core.tracker_store  - Recreating tracker for id 'ca2c5d2b07f140bb90668586f1c28b10'
? Is the intent 'ci_info' correct for '[list](count_list:List) all [impacted](impa_noimpa:Impacted) cis' and are all entities labeled correctly?  Yes
2019-06-17 19:35:30 DEBUG    rasa.core.tracker_store  - Recreating tracker for id 'ca2c5d2b07f140bb90668586f1c28b10'
2019-06-17 19:35:30 DEBUG    rasa.core.policies.memoization  - Current tracker state [None, None, None, {}, {'entity_count_list': 1.0, 'intent_ci_info': 1.0, 'slot_count_list_0': 1.0, 'slot_impa_noimpa_0': 1.0, 'prev_action_listen': 1.0, 'entity_impa_noimpa': 1.0}]
2019-06-17 19:35:30 DEBUG    rasa.core.policies.memoization  - There is a memorised next action '8'
2019-06-17 19:35:30 DEBUG    rasa.core.policies.ensemble  - Predicted next action using policy_0_MemoizationPolicy
2019-06-17 19:35:30 DEBUG    rasa.core.tracker_store  - Recreating tracker for id 'ca2c5d2b07f140bb90668586f1c28b10'
2019-06-17 19:35:30 ERROR    rasa.core.trackers  - Tried to set non existent slot 'count_list'. Make sure you added all your slots to your domain file.
2019-06-17 19:35:30 ERROR    rasa.core.trackers  - Tried to set non existent slot 'impa_noimpa'. Make sure you added all your slots to your domain file.
------
Chat History

 #    Bot                                                                                        You
────────────────────────────────────────────────────────────────────────────────────────────────────────────
 1    action_listen
────────────────────────────────────────────────────────────────────────────────────────────────────────────
 2                                         [list](count_list:List) all [impacted](impa_noimpa:Impacted) cis
                                                                                       intent: ci_info 0.96
────────────────────────────────────────────────────────────────────────────────────────────────────────────
 3    slot{"count_list": "List"}
      slot{"impa_noimpa": "Impacted"}
```

**Command or request that led to error**:
```
rasa interactive --debug --endpoints endpoints.yml
```

**Content of configuration file (config.yml)** (if relevant):
```yml


```

**Content of domain file (domain.yml)** (if relevant):
```yml

```

diff --git a/tests/core/test_trackers.py b/tests/core/test_trackers.py
index 07bd5a83762..e9056a4a764 100644
--- a/tests/core/test_trackers.py
+++ b/tests/core/test_trackers.py
@@ -5,13 +5,16 @@ import fakeredis
 import pytest
 import tempfile
 import os
+import logging
 
 import rasa.utils.io
 from rasa.core import training, restore
 from rasa.core import utils
+from rasa.core.slots import Slot
 from rasa.core.actions.action import ACTION_LISTEN_NAME
 from rasa.core.domain import Domain
 from rasa.core.events import (
+    SlotSet,
     UserUttered,
     ActionExecuted,
     Restarted,
@@ -567,3 +570,15 @@ def test_last_executed_has_not_name():
     tracker = get_tracker(events)
 
     assert tracker.last_executed_action_has("another") is False
+
+
+@pytest.mark.parametrize("key, value", [("asfa", 1), ("htb", None)])
+def test_tracker_without_slots(key, value, caplog):
+    event = SlotSet(key, value)
+    tracker = DialogueStateTracker.from_dict("any", [])
+    assert key in tracker.slots
+    with caplog.at_level(logging.INFO):
+        event.apply_to(tracker)
+        v = tracker.get_slot(key)
+        assert v == value
+    assert len(caplog.records) == 0

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==1.23.10
botocore==1.26.10
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@8775862ea6444ef47402c67c40aacb8162efdb36#egg=rasa
rasa-sdk==1.1.1
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==0.5.2
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==1.25.11
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==1.23.10
      - botocore==1.26.10
      - 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==1.1.1
      - 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==0.5.2
      - 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==1.25.11
      - 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/core/test_trackers.py::test_tracker_without_slots[asfa-1] tests/core/test_trackers.py::test_tracker_without_slots[htb-None]
[ tests/core/test_trackers.py::test_tracker_duplicate tests/core/test_trackers.py::test_tracker_store_storage_and_retrieval[redis-tracker] tests/core/test_trackers.py::test_tracker_store_storage_and_retrieval[in-memory-tracker] tests/core/test_trackers.py::test_tracker_store_storage_and_retrieval[SQL-tracker] tests/core/test_trackers.py::test_tracker_store[pair0-redis-tracker] tests/core/test_trackers.py::test_tracker_store[pair0-in-memory-tracker] tests/core/test_trackers.py::test_tracker_store[pair0-SQL-tracker] tests/core/test_trackers.py::test_tracker_store[pair1-redis-tracker] tests/core/test_trackers.py::test_tracker_store[pair1-in-memory-tracker] tests/core/test_trackers.py::test_tracker_store[pair1-SQL-tracker] tests/core/test_trackers.py::test_tracker_store[pair2-redis-tracker] tests/core/test_trackers.py::test_tracker_store[pair2-in-memory-tracker] tests/core/test_trackers.py::test_tracker_store[pair2-SQL-tracker] tests/core/test_trackers.py::test_tracker_store[pair3-redis-tracker] tests/core/test_trackers.py::test_tracker_store[pair3-in-memory-tracker] tests/core/test_trackers.py::test_tracker_store[pair3-SQL-tracker] tests/core/test_trackers.py::test_tracker_entity_retrieval tests/core/test_trackers.py::test_tracker_update_slots_with_entity tests/core/test_trackers.py::test_restart_event tests/core/test_trackers.py::test_revert_action_event tests/core/test_trackers.py::test_revert_user_utterance_event tests/core/test_trackers.py::test_traveling_back_in_time tests/core/test_trackers.py::test_get_last_event_for tests/core/test_trackers.py::test_get_last_event_with_reverted tests/core/test_trackers.py::test_get_last_event_for_with_skip tests/core/test_trackers.py::test_get_last_event_for_with_exclude tests/core/test_trackers.py::test_last_executed_has tests/core/test_trackers.py::test_last_executed_has_not_name
CHANGELOG.rst rasa/core/trackers.py
CHANGELOG.rst rasa/core/trackers.py