diff --git a/.github/workflows/integration-tests.yaml b/.github/workflows/integration-tests.yaml
index 968937e0c..c1dd01b94 100644
--- a/.github/workflows/integration-tests.yaml
+++ b/.github/workflows/integration-tests.yaml
@@ -48,8 +48,13 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-maven-
     -
+      # Must match the pyenv-installed version in dev/docker/livy-dev-base/Dockerfile.
+      # Per each Spark release's python/setup.py: Spark 4.1 supports 3.10..3.14
+      # (python_requires=">=3.10"), Spark 3.5 supports 3.8..3.11
+      # (python_requires=">=3.8"). The intersection is 3.10 and 3.11; 3.11.11
+      # is picked as the shared version.
       name: Set Python 3 as default
-      run: pyenv global 3 && echo "PYSPARK_PYTHON=$(which python3)" >> "$GITHUB_ENV"
+      run: pyenv global 3.11.11 && echo "PYSPARK_PYTHON=$(which python3)" >> "$GITHUB_ENV"
     -
       name: Set JDK version
       run: update-alternatives --set java ${{ matrix.jdk_path }}
diff --git a/dev/docker/livy-dev-base/Dockerfile b/dev/docker/livy-dev-base/Dockerfile
index 5686e61d1..b0d06b735 100644
--- a/dev/docker/livy-dev-base/Dockerfile
+++ b/dev/docker/livy-dev-base/Dockerfile
@@ -70,8 +70,17 @@ RUN git clone https://github.com/pyenv/pyenv.git $HOME/pyenv
 ENV PYENV_ROOT=$HOME/pyenv
 ENV PATH="$HOME/pyenv/shims:$HOME/pyenv/bin:$HOME/bin:$PATH"
 
-RUN pyenv install -v 3.9.21 && \
-  pyenv global 3.9.21 && \
+# Python 3.11.11 is chosen because it is in the officially supported range of
+# BOTH matrix profiles, per each Spark release's python/setup.py:
+#   * -Pspark4 (Spark 4.1.2): python_requires=">=3.10", classifiers list
+#     3.10 / 3.11 / 3.12 / 3.13 / 3.14.
+#   * -Pspark3 (Spark 3.5.6): python_requires=">=3.8", classifiers list
+#     3.8 / 3.9 / 3.10 / 3.11.
+# The intersection is 3.10 and 3.11; we pick the higher one (3.11.11) so the
+# same image serves both profiles. When bumping this, keep
+# .github/workflows/integration-tests.yaml's `pyenv global` in sync.
+RUN pyenv install -v 3.11.11 && \
+  pyenv global 3.11.11 && \
   pyenv rehash
 
 # Install build dependencies for python3
diff --git a/python-api/setup.py b/python-api/setup.py
index 4d7b9b5f2..df1a4de1e 100644
--- a/python-api/setup.py
+++ b/python-api/setup.py
@@ -37,7 +37,11 @@
 
 setup(
     name='livy-python-api',
-    version="1.0.0-SNAPSHOT",
+    # PEP 440 disallows Maven-style `-SNAPSHOT` suffixes; use `.dev0` instead,
+    # which is the canonical Python equivalent for "pre-release under active
+    # development". Modern pip (>= 24) rejects `1.0.0-SNAPSHOT` outright with
+    # `Invalid version: '1.0.0-SNAPSHOT'` when parsing this package.
+    version="1.0.0.dev0",
     packages=["livy", "livy-tests"],
     package_dir={
         "": "src/main/python",