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AdCP v2 is not supported and is not safe for interoperable production on the AgenticAdvertising.org network. v2 predates the accounts and governance protections that the AgenticAdvertising.org architecture committee considers essential for live multi-party campaigns. The last v2 release was 2.5.3 in January 2026. Begin migrating to 3.0 now.

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Timeline

The v2 sunset was not tied to 4.0. v2 reached end of life on its own schedule because 2.5 was an early, preliminary version — adoption remained small, and the architecture committee identified protections missing from v2 that could not be backported without a major redesign. v2’s shorter window is the documented exception to the 12-month previous-major support commitment; future majors will not invoke this exception.

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What “unsupported” means

As of 3.0 GA:
  • No feature work. 2.5.3 is the last v2 release. No further minor or patch work in the 2.x line, other than security advisories.
  • No AgenticAdvertising.org certification. Certification requires v3.0 or later.
  • Not verified in the AgenticAdvertising.org registry. Verified seller and agent status requires v3.x. v2-only agents can be registered but cannot be verified.
  • Frozen schemas. v2 schemas are frozen as of 2.5.3 and remain at their existing schema URLs. No new fields, tasks, or protocols.
As of August 1, 2026 (UTC), v2 is fully deprecated: security patches have stopped and reference documentation is archived. The 2.5.3 schema URLs continue to resolve so existing integrations do not break silently, but those schemas receive no further updates.

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Why v2 is not safe for interoperable production

v2 is missing protections that 3.0 treats as essential for live multi-party campaigns on the AgenticAdvertising.org network:
  • No accounts protocol. Buyers and sellers cannot negotiate account scope, operator authorization, or buyer identity resolution.
  • No governance. No structured content standards, audience bias validation, or property list governance.
  • No campaign governance. No signed proposals, approval workflow, or proposal lifecycle.
  • Limited optimization and measurement. No structured optimization goals, event source health, or streaming/audio delivery metrics.
Running v2 on the AgenticAdvertising.org network means running without these protections. Private deployments with their own governance and identity layers are the operator’s call — but the AgenticAdvertising.org network treats v2 as out of scope for supported production traffic.

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What to do

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If you run a v2 agent

  1. Read What’s new in v3.
  2. Work through the v2→v3 migration guide.
  3. Validate with storyboard testing.
  4. Complete migration as soon as possible; v2 no longer receives security patches.

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If you are a buyer integrating with v2 sellers

  1. Inventory which of your sellers are v2-only.
  2. Notify them that v2 is end of life and share the migration guide.
  3. Shift traffic to v3 sellers as they become available.

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If you use the AgenticAdvertising.org registry

Verified seller and agent status requires v3.x. v2-only agents can be registered but are not eligible for verification. As the registry rolls out verified-default discovery, v2-only entries will not surface by default; endpoints that return unverified entries remain available for operators who need them.

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Dual-support during migration

Sellers that still need a short migration bridge can support both versions using get_adcp_capabilities, adcp_version, and adcp.supported_versions — see Running v2 and v3 side by side. Through 3.x, buyers SHOULD also send the deprecated adcp_major_version, and sellers MUST continue advertising the deprecated adcp.major_versions, for compatibility with older peers. Dual-support does not make v2 supported or safe; v3-only is the required production configuration.