diff --git a/web/Dockerfile b/web/Dockerfile
index eb29a3c..4f943dc 100644
--- a/web/Dockerfile
+++ b/web/Dockerfile
@@ -16,7 +16,7 @@ RUN set -ex \
 	&& apk add --no-cache --virtual .mailman-rundeps bash sassc \
 	   postgresql-client mysql-client py3-mysqlclient curl mailcap gettext \
 	   python3 py3-pip xapian-core xapian-bindings-python3 libffi pcre-dev \
-	&& python3 -m pip install -U 'Django<3.0' pip setuptools wheel \
+	&& python3 -m pip install -U 'Django<3.1' pip setuptools wheel \
 	&& pip install mailmanclient==3.3.2 \
 		postorius==1.3.4 \
 		hyperkitty==1.3.4 \
@@ -30,6 +30,7 @@ RUN set -ex \
 		xapian-haystack \
 		django-auth-ldap \
 		python-memcached \
+		diskcache \
 	&& apk del .build-deps \
 	&& addgroup -S mailman \
 	&& adduser -S -G mailman mailman \
diff --git a/web/Dockerfile.dev b/web/Dockerfile.dev
index d4f7f3f..d3e7753 100644
--- a/web/Dockerfile.dev
+++ b/web/Dockerfile.dev
@@ -34,7 +34,8 @@ RUN set -ex \
         xapian-haystack \
         django-auth-ldap \
 		python-memcached \
-    && python3 -m pip install -U 'Django<3.0' \
+        diskcache \
+    && python3 -m pip install -U 'Django<3.1' \
     && python3 -m pip install -U \
        git+https://gitlab.com/mailman/django-mailman3@${DJ_MM3_REF} \
     && apk del .build-deps \
diff --git a/web/mailman-web/settings.py b/web/mailman-web/settings.py
index b8d9c60..8c3aba6 100644
--- a/web/mailman-web/settings.py
+++ b/web/mailman-web/settings.py
@@ -46,7 +46,7 @@ ADMINS = (
 SITE_ID = 1
 
 # Hosts/domain names that are valid for this site; required if DEBUG is False
-# See https://docs.djangoproject.com/en/1.8/ref/settings/#allowed-hosts
+# See https://docs.djangoproject.com/en/3.1/ref/settings/#allowed-hosts
 ALLOWED_HOSTS = [
     "localhost",  # Archiving API from Mailman, keep it.
     # "lists.your-domain.org",
@@ -91,6 +91,7 @@ DEFAULT_APPS = [
     'allauth.account',
     'allauth.socialaccount',
 ]
+
 MAILMAN_WEB_SOCIAL_AUTH = [
     'django_mailman3.lib.auth.fedora',
     'allauth.socialaccount.providers.openid',
@@ -143,9 +144,7 @@ WSGI_APPLICATION = 'wsgi.application'
 
 # Database
 # https://docs.djangoproject.com/en/1.8/ref/settings/#databases
-
-
-# This uses $DATABASE_URL from the environment variable to create a
+# dj_database_url uses $DATABASE_URL environment variable to create a
 # django-style-config-dict.
 # https://github.com/kennethreitz/dj-database-url
 DATABASES = {
@@ -161,20 +160,16 @@ USE_X_FORWARDED_HOST = True
 # https://docs.djangoproject.com/en/1.9/ref/settings/#auth-password-validators
 AUTH_PASSWORD_VALIDATORS = [
     {
-        'NAME':
-'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
+        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
     },
     {
-        'NAME':
-'django.contrib.auth.password_validation.MinimumLengthValidator',
+        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
     },
     {
-        'NAME':
-'django.contrib.auth.password_validation.CommonPasswordValidator',
+        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
     },
     {
-        'NAME':
-'django.contrib.auth.password_validation.NumericPasswordValidator',
+        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
     },
 ]
 
@@ -343,8 +338,6 @@ LOGGING = {
             'level': 'INFO',
             'stream': sys.stdout,
         },
-        # TODO: use an environment variable $DJ_LOG_URL to configure the logging
-        # using an environment variable.
     },
     'loggers': {
         'django.request': {
@@ -376,16 +369,13 @@ LOGGING = {
             'format': '%(levelname)s %(message)s'
         },
     },
-    #'root': {
-    #    'handlers': ['file'],
-    #    'level': 'INFO',
-    #},
 }
 
 
 if os.environ.get('LOG_TO_CONSOLE') == 'yes':
     LOGGING['loggers']['django']['handlers'].append('console')
     LOGGING['loggers']['django.request']['handlers'].append('console')
+
 # HyperKitty-specific
 #
 # Only display mailing-lists from the same virtual host as the webserver
@@ -401,6 +391,16 @@ Q_CLUSTER = {
 
 POSTORIUS_TEMPLATE_BASE_URL =  os.environ.get('POSTORIUS_TEMPLATE_BASE_URL', 'http://mailman-web:8000')
 
+CACHES = {
+    'default': {
+        'BACKEND': 'diskcache.DjangoCache',
+        'LOCATION': '/opt/mailman-web-data/diskcache',
+        'OPTIONS': {
+            'size_limit': 2 ** 30   # 1 gigabyte
+        },
+    },
+}
+
 try:
     from settings_local import *
 except ImportError: