diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5575a9c57..04bc9605e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,35 @@ Categories: Added, Removed, Changed, Fixed, Nonfunctional, Deprecated
 
 ## Unreleased
 
-- Fix recursion in sceptre_user_data becoming infinite
+## 2.2.1 (2019.08.19)
+
+### Fixed
+
+- `typing` install dependency for Python version < 3.5
+- Race condition in stacks causing RecurrsiveGet exception
+
+## 2.2.0 (2019.08.16)
+
+### Added
+
+- Meaningful Jinja Template exception output handling
+
+### Fixed
+
+- Recursion in `sceptre_user_data` becoming infinite
+- AWS `rate_exceeded` error when hitting AWS API too frequently
+- Readme links
+- StackGraph debugging output
+
+### Nonfunctional
+
+- Moved CircleCI Dockerfile to its own repository
+- Add SonarQube analysis
+- Change CircleCI setup to use context over environment variables
+- Removed redundant test code
+- Add badges to README
+- Adjust Coverage fail-level to 92%
+- Update CONTRIBUTING Guide
 
 ## 2.1.5 (2019.06.28)
 
diff --git a/requirements/prod.txt b/requirements/prod.txt
index 3e2dab356..3e1894eb7 100644
--- a/requirements/prod.txt
+++ b/requirements/prod.txt
@@ -4,3 +4,4 @@ colorama==0.3.9
 Jinja2>=2.8,<3
 networkx==2.1
 PyYaml>=5.1,<6.0
+typing>=3.7,<3.8
diff --git a/sceptre/__init__.py b/sceptre/__init__.py
index caf82efe6..99b6b0a81 100644
--- a/sceptre/__init__.py
+++ b/sceptre/__init__.py
@@ -6,7 +6,7 @@
 
 __author__ = 'Cloudreach'
 __email__ = 'sceptre@cloudreach.com'
-__version__ = '2.1.5'
+__version__ = '2.2.1'
 
 
 # Set up logging to ``/dev/null`` like a library is supposed to.
diff --git a/sceptre/connection_manager.py b/sceptre/connection_manager.py
index ffe78fbfe..6b143ece4 100644
--- a/sceptre/connection_manager.py
+++ b/sceptre/connection_manager.py
@@ -55,8 +55,8 @@ def decorated(*args, **kwargs):
                     time.sleep(mdelay)
 
                     # Using De-correlated Jitter Algorithm
-                    # We are picking number between a ceiling (delay_cap) of 45 seconds and the last
-                    # delay multiplied by 2.5, rounding to two decimal places.
+                    # We are picking number between a ceiling (delay_cap) of 45 seconds and the
+                    # last delay multiplied by 2.5, rounding to two decimal places.
                     mdelay = min(delay_cap, round((random.uniform(1, mdelay * 2.5)), 2))
 
                     attempts += 1
diff --git a/sceptre/resolvers/__init__.py b/sceptre/resolvers/__init__.py
index 897ace858..846ee2076 100644
--- a/sceptre/resolvers/__init__.py
+++ b/sceptre/resolvers/__init__.py
@@ -2,6 +2,7 @@
 import abc
 import logging
 from contextlib import contextmanager
+from threading import RLock
 
 import six
 from sceptre.helpers import _call_func_on_values
@@ -64,6 +65,7 @@ def __init__(self, name):
         self.name = "_" + name
         self.logger = logging.getLogger(__name__)
         self._get_in_progress = False
+        self._lock = RLock()
 
     def __get__(self, instance, type):
         """
@@ -73,7 +75,7 @@ def __get__(self, instance, type):
         :return: The attribute stored with the suffix ``name`` in the instance.
         :rtype: dict or list
         """
-        with self._no_recursive_get():
+        with self._lock, self._no_recursive_get():
             def resolve(attr, key, value):
                 try:
                     attr[key] = value.resolve()
@@ -97,8 +99,9 @@ def setup(attr, key, value):
             value.stack = instance
             value.setup()
 
-        _call_func_on_values(setup, value, Resolver)
-        setattr(instance, self.name, value)
+        with self._lock:
+            _call_func_on_values(setup, value, Resolver)
+            setattr(instance, self.name, value)
 
     class ResolveLater(object):
         """Represents a value that could not yet be resolved but can be resolved in the future."""
diff --git a/setup.cfg b/setup.cfg
index 6750f5f21..b6f761ad9 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 2.1.5
+current_version = 2.2.1
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)|(?P<release_candidate>.*)
 commit = True
 tag = True
diff --git a/setup.py b/setup.py
index 1f1da85ff..57fc7a5d8 100755
--- a/setup.py
+++ b/setup.py
@@ -19,7 +19,8 @@
     "colorama==0.3.9",
     "packaging==16.8",
     "six>=1.11.0,<2.0.0",
-    "networkx==2.1"
+    "networkx==2.1",
+    "typing>=3.7.0,<3.8.0"
 ]
 
 test_requirements = [