104005: Session send failed

An AI Transport send or steer could not be delivered. Either publishing it to the channel failed, or, in the Vercel chat transport, the HTTP POST to the agent endpoint failed with a network error or a non-2xx response.

What you should do

This fails in one of two ways:

• A channel publish failed (a send or a steer). Inspect the cause, which carries the underlying publish failure and its own error code, for what went wrong and how to fix it.
• The Vercel chat transport's HTTP POST failed. The request to your agent-invocation endpoint returned a non-2xx response, surfaced with the status the endpoint returned, or errored outright. Check that the endpoint is reachable and returns a 2xx.

Neither a send nor a steer is retried automatically, so reissue it once the underlying problem is resolved.

Why it happens

A send or steer publishes to the channel; in the Vercel chat transport a send instead POSTs to your agent-invocation endpoint, which publishes on the agent's behalf. This error is the non-permission failure of either path (a permission failure is reported separately as a capability error). The originating failure is preserved as the cause where available.

What you'll see

The error is reported with code 104005. Its status is 500 for a failed channel publish; for a non-2xx POST it is the status the agent endpoint returned. Messages take the form unable to publish events; ..., unable to publish steer; ..., or unable to send; HTTP POST to ... returned ....