---
id: feature/573352
type: feature
title: Evolve AL interfaces with default implementations
summary: 'Development: Evolve AL interfaces with default implementations. Generally available, GA 2026-10 (Microsoft 365 roadmap). "Add default method bodies to AL interfaces so existing implementors continue working, then use RequiredPending and analyzer rules to introduce required methods safely. Business value: Extension publishers can add behavior to an interface without immediately requiring every implementing extension to change.'
tier: official
language: en
system: development
tags:
  - development
review:
  state: derived
  by: null
  at: null
  flags: []
generated:
  at: "2026-10-07T23:41:05.192Z"
  pipeline: 0.2.0
  prompts: {}
  input_hash: 5d0be513a46564e3169e091e8ef0a01cc129838868f3a3e52410201adf10d80e
evidence:
  - kind: roadmap
    url: https://www.microsoft.com/microsoft-365/roadmap?id=573352
    title: Microsoft 365 roadmap 573352
    date: "2026-09-30"
    commit: null
    t: null
    quote: null
  - kind: video
    url: https://www.youtube.com/watch?v=D_Lur52IrIg&t=458s
    title: "What's new in AL and Tools (2026 release wave 2): Interface default implementations"
    date: null
    commit: null
    t: 458
    quote: null
  - kind: video
    url: https://www.youtube.com/watch?v=H_PHi8pe53w&t=254s
    title: "Business Central 29 0 Default Implementations in AL Interfaces: Default implementation for AL interfaces"
    date: null
    commit: null
    t: 254
    quote: null
  - kind: video
    url: https://www.youtube.com/watch?v=H_PHi8pe53w&t=532s
    title: "Business Central 29 0 Default Implementations in AL Interfaces: Required pending attribute for AL interface methods"
    date: null
    commit: null
    t: 532
    quote: null
  - kind: video
    url: https://www.youtube.com/watch?v=MNwTt06ZxwY&t=1430s
    title: "Microsoft presents: Building and shipping agents in Business Central: Optional interface methods"
    date: null
    commit: null
    t: 1430
    quote: null
  - kind: learn
    url: https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/devenv-interface-method-lifecycle
    title: Interface method lifecycle
    date: null
    commit: null
    t: null
    quote: null
  - kind: learn
    url: https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/devenv-interfaces-in-al
    title: Interfaces in AL
    date: null
    commit: null
    t: null
    quote: null
links:
  learn:
    - https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/devenv-interface-method-lifecycle
    - https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/devenv-interfaces-in-al
  objects: []
  features: []
  topics: []
  localizations: []
  videos:
    - video/D_Lur52IrIg
    - video/H_PHi8pe53w
    - video/MNwTt06ZxwY
  posts: []
  guidelines: []
roadmap_id: "573352"
wave: 2026 release wave 2
status: ga
roadmap_status: Launched
release_phase: General Availability
ga_date: 2026-10
preview_date: null
area: Development
whatsnew_url: null
localizations: []
objects_touched: []
---

# Evolve AL interfaces with default implementations

> Development: Evolve AL interfaces with default implementations. Generally available, GA 2026-10 (Microsoft 365 roadmap). "Add default method bodies to AL interfaces so existing implementors continue working, then use RequiredPending and analyzer rules to introduce required methods safely. Business value: Extension publishers can add behavior to an interface without immediately requiring every implementing extension to change.

[Microsoft 365 roadmap 573352](https://www.microsoft.com/microsoft-365/roadmap?id=573352) · Development · generally available · roadmap status "Launched", phase General Availability

## What Microsoft says

"Add default method bodies to AL interfaces so existing implementors continue working, then use RequiredPending and analyzer rules to introduce required methods safely. Business value: Extension publishers can add behavior to an interface without immediately requiring every implementing extension to change. Default methods provide a compatible implementation, while the new transition attribute and AppSourceCop rules support a managed path toward making a method mandatory in a future version. This reduces disruptive interface upgrades and gives dependent developers time to adopt new contracts."

## Dates

- General availability: October CY2026 (2026 release wave 2)
- Public preview: not given
- On the roadmap since 2026-09-30, last changed 2026-09-30

## Covered by

Matched by Haiku among videos and Learn pages in the same galaxy system, checked against the roadmap ids and the evidence text. Every link below was reviewed by Opus.

### Videos

- [What's new in AL and Tools (2026 release wave 2)](../videos/D_Lur52IrIg.md): Interface default implementations at [7:38](https://www.youtube.com/watch?v=D_Lur52IrIg&t=458s)
- [Business Central 29 0 Default Implementations in AL Interfaces](../videos/H_PHi8pe53w.md): Default implementation for AL interfaces at [4:14](https://www.youtube.com/watch?v=H_PHi8pe53w&t=254s); Required pending attribute for AL interface methods at [8:52](https://www.youtube.com/watch?v=H_PHi8pe53w&t=532s)
- [Microsoft presents: Building and shipping agents in Business Central](../videos/MNwTt06ZxwY.md): Optional interface methods at [23:50](https://www.youtube.com/watch?v=MNwTt06ZxwY&t=1430s)

### Microsoft Learn

- [Interface method lifecycle](https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/devenv-interface-method-lifecycle)
- [Interfaces in AL](https://learn.microsoft.com/dynamics365/business-central/dev-itpro/developer/devenv-interfaces-in-al)

Source: Microsoft 365 roadmap. Status words follow the roadmap.