diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index fc3ee239..db627db5 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -58,9 +58,9 @@ jobs:
     # To save arm64 runner resources, we run the tests only on main
     # and only for full-stack image (same for integration tests below).
     test-arm64:
-        if: >-
-            github.repository == 'aiidalab/aiidalab-docker-stack'
-            && (github.ref_type == 'tag' || github.ref_name == 'main')
+        #if: >-
+        #    github.repository == 'aiidalab/aiidalab-docker-stack'
+        #    && (github.ref_type == 'tag' || github.ref_name == 'main')
         needs: build
         uses: ./.github/workflows/test.yml
         with:
@@ -80,9 +80,9 @@ jobs:
                 runner: [ubuntu-22.04, buildjet-4vcpu-ubuntu-2204-arm]
                 isPR:
                     - ${{ github.event_name == 'pull_request' }}
-                exclude:
-                    - isPR: true
-                      runner: buildjet-4vcpu-ubuntu-2204-arm
+                #exclude:
+                    #    - isPR: true
+                    #  runner: buildjet-4vcpu-ubuntu-2204-arm
 
         uses: ./.github/workflows/test.yml
         with:
diff --git a/build.json b/build.json
index f016bced..606ddcaa 100644
--- a/build.json
+++ b/build.json
@@ -1,7 +1,7 @@
 {
   "variable": {
     "PYTHON_VERSION": {
-      "default": "3.9.13"
+      "default": "3.11.3"
     },
     "PGSQL_VERSION": {
       "default": "15"
diff --git a/stack/base/Dockerfile b/stack/base/Dockerfile
index 00257807..5b7cc270 100644
--- a/stack/base/Dockerfile
+++ b/stack/base/Dockerfile
@@ -59,12 +59,13 @@ COPY pip.conf "${CONDA_DIR}/pip.conf"
 # Upgrade pip and mamba to latest
 # Update async_generator, certipy to satisfy `pip check`
 # https://github.com/aiidalab/aiidalab-docker-stack/issues/490
+# Update zstandard, without this the `mamba install` command fails for unknown reason.
 # Install aiida-core and other shared requirements.
-RUN mamba update -y pip async_generator certipy && \
+RUN mamba update -y pip zstandard async_generator certipy && \
      mamba install --yes \
+     mamba=1.5 \
      aiida-core==${AIIDA_VERSION} \
      mamba-bash-completion \
-     traitlets=5.9.0 \
      && mamba clean --all -f -y && \
      fix-permissions "${CONDA_DIR}"
 
diff --git a/stack/lab/Dockerfile b/stack/lab/Dockerfile
index 3bcb97bd..a65e4415 100644
--- a/stack/lab/Dockerfile
+++ b/stack/lab/Dockerfile
@@ -30,9 +30,8 @@ RUN echo 'eval "$(_AIIDALAB_COMPLETE=bash_source aiidalab)"' >> "${CONDA_DIR}/et
 
 # Install the aiidalab-home app.
 ARG AIIDALAB_HOME_VERSION
-RUN git clone https://github.com/aiidalab/aiidalab-home && \
+RUN git clone --branch fix/single_app_crash https://github.com/aiidalab/aiidalab-home && \
      cd aiidalab-home && \
-     git checkout v"${AIIDALAB_HOME_VERSION}" && \
      pip install --no-user --quiet --no-cache-dir "./" && \
      fix-permissions "./" && \
      fix-permissions "${CONDA_DIR}" && \
@@ -77,7 +76,7 @@ WORKDIR "/home/${NB_USER}"
 
 RUN  mkdir -p /home/${NB_USER}/apps
 
-# When a Jupyter notebook server looses a connection to the frontend,
+# NOTE1: When a Jupyter notebook server looses a connection to the frontend,
 # it keeps the messages in a buffer. If there is a background thread running
 # and trying to update the frontend, the buffer grows indefinitely,
 # eventually consuming all available RAM.
@@ -87,8 +86,10 @@ RUN  mkdir -p /home/${NB_USER}/apps
 # but that may come with other problems for people with flaky internet connections.
 # Instead, here we configure Jupyter to kill all kernels that have been alive for
 # more than 12 hours. We also close all inactive terminals after 10 minutes.
+# NOTE2: show_banner=False disables the banner for upgrading to Notebook 7.
 ENV NOTEBOOK_ARGS \
      "--NotebookApp.default_url='/apps/apps/home/start.ipynb'" \
+     "--NotebookApp.show_banner=False" \
      "--ContentsManager.allow_hidden=True" \
      "--MappingKernelManager.buffer_offline_messages=True" \
      "--MappingKernelManager.cull_busy=True" \