Guidance Request: Choosing Between Python 3.12 and 3.13 for Azure Functions (Runtime 4.0)

Hi @EBT

Thank you for reaching out to Microsoft Q&A.

Both Python 3.12 and Python 3.13 are fully supported (GA) on Azure Functions Runtime 4.0 when running on an App Service Plan. There is no functional issue preventing either version from working with your current setup or the Azure SDK libraries you are using (azure-core, azure-functions, azure-storage-blob, azure-storage-queue). The decision point is not about something “not working,” but about choosing the most appropriate and future‑proof Python version. Python 3.13 is the newer GA release for Azure Functions, offers a longer support lifecycle, and introduces runtime-level improvements (such as Python worker runtime version control and improved dependency isolation). Python 3.12 remains a stable and supported option, but it has a shorter support window and does not include some of the newer runtime capabilities introduced with Python 3.13.

Refer below points to resolve this issue or this is the workaround

Use Python 3.13 for new or actively developed Azure Functions apps

• Python 3.13 is GA on Azure Functions Runtime 4.0 and has the longest support timeline compared to Python 3.12.
• It is the recommended choice for App Service Plan–based Function Apps where long-term maintainability and reduced future upgrades are important.

Take advantage of Python 3.13 runtime version control (optional)

• Starting with Python 3.13, Azure Functions allows you to control the Python worker runtime version via requirements.txt.
• You can either stay on the latest stable worker automatically or pin to a specific version once validated in lower environments.

# Example (do not pin to prerelease versions for production)
azure-functions-runtime

Continue using Python 3.12 if you need a conservative or compatibility-first approach

• Python 3.12 is still fully supported (GA) on Azure Functions Runtime 4.0.
• This may be preferred if internal standards, compliance requirements, or third‑party dependencies are already standardized on Python 3.12.

No library changes are required for either option

• The Azure SDK libraries you listed (azure-core, azure-functions, azure-storage-blob, azure-storage-queue) are supported on both Python 3.12 and Python 3.13.
• No code changes are required solely due to the Python version upgrade.

Final recommendation

• For new deployments: Python 3.13
• For existing workloads prioritizing minimal change: Python 3.12, with a planned upgrade to 3.13 later

Hello EBT,

For new Azure Functions v4 deployments on an App Service Plan, Python 3.13 is the recommended runtime. It is fully supported (GA), offers the longest support lifecycle, and includes runtime‑level improvements that reduce dependency conflicts and improve maintainability. Python 3.12 remains a supported and stable alternative if required for compatibility reasons.

Python 3.13 GA announcement for Azure Functions

Azure Functions Runtime v4.0 (GA) supports both Python 3.12 and Python 3.13 on Linux hosting, including App Service Plans.

Python 3.13 has the latest end‑of‑support timeline, making it more future‑proof than 3.12 for production systems.

Starting with Python 3.13, Azure Functions introduces:

• Runtime version control (opt‑in)
• Improved dependency isolation between your app packages and the Functions Python worker
• Reduced risk of package version conflicts for libraries such as:
• azure-core
• azure-functions
• azure-storage-blob
  • azure-storage-queue

These improvements are GA and specifically available for 3.13 workloads.

You may prefer Python 3.12 if:

• You require absolute stability with conservative change management
• Internal tooling, compliance, or validation processes are already pinned to 3.12
• You are aligning with another platform still standardizing on 3.12

Python 3.12 remains fully supported and production‑ready on Functions v4.

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For an Azure Functions v4 app on an App Service plan using the listed Azure SDK libraries, Python 3.13 is the better long‑term choice, with Python 3.12 as a solid alternative if 3.13‑specific features are not yet needed.

Key points from the current platform support:

1. Both 3.12 and 3.13 are fully supported (GA) on Functions v4
   The supported Python versions for Azure Functions include:
   • Python 3.10 (GA, EOS October 2026)
   • Python 3.11 (GA, EOS October 2027)
   • Python 3.12 (GA, EOS October 2028)
   • Python 3.13 (GA, EOS October 2029)
   Python 3.13 has the longest support window, which is important for production workloads.
2. Linux Consumption limitation does not affect an App Service plan
   The note that Python 3.12 is the last version supported on Linux Consumption applies only to that plan type.
   Since the environment is an App Service plan (not Linux Consumption), it can use newer versions like Python 3.13.
3. Python 3.13 introduces runtime improvements and dependency isolation
   For Python 3.13+ function apps, Azure Functions adds:
   • Optional runtime version control via the azure-functions-runtime-v1 package in requirements.txt, allowing pinning to a specific Functions Python worker version or staying on the latest.
   • Dependency isolation between the app’s packages (such as azure-core, azure-functions, azure-storage-blob, azure-storage-queue) and the worker’s own dependencies, reducing version conflicts.
   • The PYTHON_ISOLATE_WORKER_DEPENDENCIES setting no longer applies for Python 3.13+ apps.
4. Recommended choice for new development
   Given:
   • App Service plan (no Linux Consumption constraint),
   • Standard Azure SDK libraries in use, and
   • Longer support horizon and improved runtime behavior,
   Python 3.13 is recommended for new or actively developed Azure Functions apps. For production stability, consider:
   • Using azure-functions-runtime-v1 without a pinned version to stay on the latest stable runtime, or
   • Pinning to a specific version (for example, azure-functions-runtime-v1==x.y.z) once validated in non‑production, if strict stability is required.
5. When to choose Python 3.12 instead
   Python 3.12 remains a valid choice if:
   • There are existing internal constraints or testing baselines on 3.12, or
   • A dependency has not yet been validated on 3.13.
   In that case, 3.12 still provides a long support window (to October 2028) and is fully supported on Functions v4.

Summary:

• Prefer Python 3.13 for new Azure Functions v4 apps on an App Service plan, to benefit from the latest runtime improvements, dependency isolation, and the longest support period.
• Use Python 3.12 only if there are specific compatibility or validation reasons to stay on that version.

References:

• Azure Functions runtime versions overview (programming-language-python)
• Azure Functions developer reference guide for Python apps (python-mode-decorators)
• Azure Functions developer reference guide for Python apps (python-mode-configuration)
• Supported languages in Azure Functions (programming-language-python)