invalid_card

Invalid A2A Card. Answered with 400.

What it means

The A2A Card patch was refused: a field is missing, empty, or not the type the A2A specification gives it. The detail names the field.

What to do

Fix the field the detail names and send the patch again. Read the card first if you are unsure what it holds now.

The body

{
  "type": "https://tigby.eu/problems/invalid_card",
  "title": "Invalid A2A Card",
  "status": 400,
  "detail": "…what was refused, naming this request's own values",
  "code": "invalid_card",
  "doc_url": "https://docs.tigby.eu/errors/invalid_card",
  "agent_hint": "…the next step, for software"
}

Branch on code. The detail names this request's own Handle, id or limit and is not part of the contract.