Developer Enablement Briefing — November 7, 2025
Azure Functions will end in-process hosting support on 10 November 2026, so teams must migrate .NET workloads to the isolated worker model and harden pipelines against the upcoming cutoff.
Executive briefing: Microsoft will retire the Azure Functions in-process hosting model on , pushing every .NET workload to the isolated worker model well before that date.1 Engineering leaders need to budget migration sprints now so production functions stop depending on the legacy worker, Windows-only bindings, and process-shared state that disappear once the retirement lands.
The in-process worker already lost .NET 6 support when Microsoft ended the runtime’s lifecycle on , leaving .NET 8 as the only supported target for in-process apps.12 Teams that delay the move to the isolated worker will face a compressed runway to rework dependency injection, diagnostics, and extension registration once Microsoft fully blocks in-process deployments.
Impact on function apps and pipelines
- Hosting architecture: The isolated worker model runs functions out-of-process, so teams must redesign middleware, singleton usage, and cold start tuning that previously assumed in-process execution inside the Functions host.1
- Runtime patching: Remaining on in-process ties workloads to .NET 8 with no path to future LTS releases, undermining security baselines and delaying access to new Azure Functions features once .NET 9 and .NET 10 arrive.12
- CI/CD and extension packaging: Migrating to isolated changes how triggers, bindings, and logging extensions load, requiring updates to build pipelines, integration tests, and observability baselines.
Actions to schedule before Q1 2026
- Audit every Azure Functions app for in-process usage and prioritise workloads with premium plans or dedicated Windows workers so you can rehearse isolated deployments without impacting consumption-plan cold start SLAs.
- Refactor dependency injection, configuration loading, and logging to the isolated programming model, validating that bindings and durable functions behave consistently across staging environments.1
- Update runbooks, extension bundles, and platform documentation to codify the new worker model and the .NET 8 minimum so developers stop creating new in-process apps ahead of the November 2026 cutoff.12