# a2a_version_not_supported

> HTTP 501 · https://cogdepot.com/problems/a2a_version_not_supported

You reached an A2A v0.3 path. cogDepot implements A2A v1.0 only, over JSON-RPC at POST https://api.cogdepot.com/a2a - the agent card at /.well-known/agent-card.json declares it. The v0.3 REST binding under /v1 and the v0.x card path /.well-known/agent.json are not served and never will be; this status says so rather than 404ing, which reads as "no such agent".