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title: A2A Connector 2.0 Troubleshooting
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locale: en-us
portal_url: https://docs.salesforce.com/mulesoft/current/en-us/a2a-connector/latest/a2a-connector-troubleshooting.md
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release: "2.0"
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---
product: A2A Connector
version: 2.0
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---

# A2A Connector 2.0 Troubleshooting

> For the full documentation index, see: https://docs.mulesoft.com/llms.txt

To troubleshoot Anypoint Connector for A2A (A2A Connector), become familiar with the information
about performing general troubleshooting, addressing specific common errors, and interpreting
commonly thrown exception messages.

## Error Unmarshalling String JSON Payload into Type io.a2a.spec.Task. Cause: Argument "content" is Null

Likely cause:

- The payload maps to a task or message schema that expects a non-null text content field, but
  received `null`.

Resolution checklist:

- Ensure every text part includes a non-empty `text` value.

- Avoid sending `content: null` or equivalent nullable fields in message or task parts.

- Validate outbound JSON in Studio using connector metadata types before sending.

- Confirm your DataWeave transformation outputs JSON objects, not quoted JSON strings.

## Failed to Establish SSE Connection

Likely causes:

- Request is sent as a non-streaming `SendMessage` instead of `SendStreamingMessage` (JSON-RPC), or
  to `POST /message:send` instead of `POST /message:stream` (HTTP+JSON).

- The server app doesn’t include an active **A2A Server - Task Listener** flow.

- The agent card does not advertise `capabilities.streaming: true`.

- Reverse proxy or gateway strips `text/event-stream` semantics or closes long-lived HTTP
  connections.

Resolution checklist:

- Verify the method is `SendStreamingMessage` (JSON-RPC) or the request targets
  `POST /message:stream` (HTTP+JSON).

- Verify the server flow includes an **A2A Server - Task Listener**. The unified task listener
  serves streaming requests. There is no separate **A2A Server - On Task Stream Listener** in 2.0.

- Confirm the agent card advertises `capabilities.streaming: true`.

- Confirm HTTP 200 response with `Content-Type: text/event-stream`.

- Check timeout and keepalive settings in intermediary proxies and load balancers.

## A2A Server Config Errors Despite Correct Configuration

Likely causes:

- Invalid **Agent Path** to listener route binding.

- Card file path not found at runtime.

- Agent card JSON is malformed or missing capability metadata expected by clients.

Resolution checklist:

- Use `${app.home}/agent-card.json` when deploying to CloudHub.

- Validate card JSON syntax and required top-level fields.

- Confirm `<a2a:connection listenerConfig="…​" agentPath="…​"/>` references a valid
  `http:listener-config`.

- Check app startup logs for binding or card parsing errors before runtime requests.

## See Also

- [A2A Connector Examples](https://docs.mulesoft.com/a2a-connector/latest/a2a-connector-examples)

- [A2A Connector Reference](https://docs.mulesoft.com/a2a-connector/latest/a2a-connector-reference)

- [Salesforce Help](https://help.salesforce.com)

- [Known Issues](https://help.salesforce.com/s/issues)