diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index f55e68a..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,28 +0,0 @@
-language: python
-sudo: require
-python:
-  - "3.6"
-  - "3.7"
-  - "3.8"
-# command to install dependencies
-install:
-  - pip install -r requirements.txt
-  - pip install coveralls
-
-# command to run tests
-script:
-  - python -m compileall ./
-  - coverage run --omit='*/virtualenv/*,*/site-packages/*,*/tests/*' -m unittest discover -s . -v -p "*_test.py"
-
-# create coverage for one python version
-after_success:
-  - test $TRAVIS_PYTHON_VERSION == "3.8" && coveralls
-
-notifications:
-  email: false
-
-deploy:
-  provider: script
-  script: curl https://rico-j.de/travis/deploy-bj.sh
-  on:
-    branch: master
diff --git a/blackjackbot/lang/custom_strings/README.md b/blackjackbot/lang/custom_strings/README.md
new file mode 100644
index 0000000..cb39225
--- /dev/null
+++ b/blackjackbot/lang/custom_strings/README.md
@@ -0,0 +1,9 @@
+## custom_strings directory
+
+This directory was created to add translations on the fly, when the bot runs inside a docker container.
+
+```
+└───lang
+    ├───custom_strings  // custom translations
+    └───strings         // translations provided by the package maintainer
+```
diff --git a/requirements.txt b/requirements.txt
index 7b46adf..49e88a4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1 @@
-python-telegram-bot==13.1
+python-telegram-bot>=13.5
diff --git a/util/banneduserhandler.py b/util/banneduserhandler.py
index 485aebe..64b4cac 100644
--- a/util/banneduserhandler.py
+++ b/util/banneduserhandler.py
@@ -1,13 +1,23 @@
 # -*- coding: utf-8 -*-
+import logging
+
 from telegram.ext import TypeHandler
 
 import database
 
 
 class BannedUserHandler(TypeHandler):
+    logger = logging.getLogger()
 
     def check_update(self, update):
         db = database.Database()
-        if db.is_user_banned(update.effective_user.id):
+        user = update.effective_user
+
+        if user is None:
+            self.logger.warning(f"User is None! Update: {update}")
+            return False
+
+        if db.is_user_banned(user.id):
             return True
+
         return False