# Fix "does not allow /v1/messages dispatch" and /v1/messages 400s

> Why Claude Code or the Anthropic SDK gets "This group does not allow /v1/messages dispatch" or a 400 on /v1/messages, and which models and settings fix it on BigModel.io.

Web version: https://bigmodel.io/docs/error-messages-dispatch · Updated 2026-10-27

Claude Code and the Anthropic SDKs call `POST /v1/messages`. Two errors mean that this endpoint is not available for the model or key you used:

```json
{ "type": "error", "error": { "type": "permission_error", "message": "This group does not allow /v1/messages dispatch" } }
```

```json
{ "type": "error", "error": { "type": "invalid_request_error", "message": "`X` does not support the Anthropic Messages API (/v1/messages, used by Claude Code) yet. Models that do: ... Or call /v1/chat/completions or /v1/responses." } }
```

## What it means

`/v1/messages` serves only models whose endpoints include it. Today those are **`glm-5.3`, `kimi-k3` and `deepseek-v4-flash`**. Every text model works on `/v1/chat/completions`, and the [model catalog](https://bigmodel.io/models) lists the endpoints of each model.

- The **400** names the models that do support the Messages API. Pick one of them.
- The **403 "does not allow /v1/messages dispatch"** only appears when a request is not matched to a catalog model. On BigModel.io you normally get the 400 above, or a 404 for an unknown model ID. Using a supported model ID fixes both.

If you saw this 403 on another service, its operator has to enable Messages for your key there.

## How to fix it

1. Set the model to one that supports `/v1/messages`. In Claude Code, set all model slots, because background tasks use the haiku slot:

```bash
export ANTHROPIC_BASE_URL="https://bigmodel.io"
export ANTHROPIC_AUTH_TOKEN="$BIGMODEL_API_KEY"
export ANTHROPIC_MODEL="glm-5.3"
export ANTHROPIC_DEFAULT_OPUS_MODEL="glm-5.3"
export ANTHROPIC_DEFAULT_SONNET_MODEL="glm-5.3"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="deepseek-v4-flash"
```

2. Check the base URL: `https://bigmodel.io` without `/v1`. Claude Code adds `/v1/messages` itself.
3. To use a model without Messages support, call it from an OpenAI-compatible client on `https://bigmodel.io/v1/chat/completions` instead.

## Troubleshooting

**The error names a `claude-*` model.** Claude Code fell back to its default model because a slot is unset. Set every `ANTHROPIC_DEFAULT_*_MODEL` value. See [Model not found](https://bigmodel.io/docs/error-model-not-found).

**It worked yesterday with the same model.** Check the [changelog](https://bigmodel.io/docs/changelog) and the model's page for endpoint changes, then contact [Support](https://bigmodel.io/support) with the `X-Request-ID`.

## Related

- [Use BigModel.io with Claude Code](https://bigmodel.io/docs/claude-code)
- [Create a message (Anthropic Messages)](https://bigmodel.io/docs/api-messages)
- [Error codes and responses](https://bigmodel.io/docs/errors)