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outline: deep
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# DF0050: No Devframe Instance on Port

## Message

> No running devframe instance on port `{port}`.

## Cause

The `devframe connect` gateway tool `devframe_connect_call-tool` targeted a port with no live devframe instance behind it — neither the instance registry nor a direct probe of the port found one serving `__connection.json`. The instance may have stopped, restarted on a different port, or never existed. The error crosses the MCP boundary as structured JSON, so the calling agent can self-correct.

## Example

```ts
// No dev server on 5199:
// devframe_connect_call-tool({ port: 5199, tool: 'devframe_state_read' }) → DF0050
```

## Fix

Call `devframe_connect_list-instances` for the current instance list and retry with a live port.

## Source

- [`packages/devframe/src/cli/connect.ts`](https://github.com/devframes/devframe/blob/main/packages/devframe/src/cli/connect.ts) — `call()` throws this when neither the registry nor the port probe finds an instance.
