langflow-ai/langflow · error · HTTPException

{body.client.capitalize()} is not installed on this system.

Error message

{body.client.capitalize()} is not installed on this system. Please install {body.client.capitalize()} first.

What it means

Error "{body.client.capitalize()} is not installed on this system. Please install {body.client.capitalize()} first." thrown in langflow-ai/langflow.

Source

Thrown at src/backend/base/langflow/api/v1/mcp_projects.py:965

        # Create the MCP configuration
        server_config: dict[str, Any] = {
            "command": command,
            "args": args,
        }

        mcp_config = {"mcpServers": {server_name: server_config}}

        await logger.adebug("Installing MCP config for project: %s (server name: %s)", project.name, server_name)

        # Get the config file path and check if client is available
        try:
            config_path = await get_config_path(body.client.lower())
        except ValueError as e:
            raise HTTPException(status_code=400, detail=str(e)) from e

        # Check if the client application is available (config directory exists)
        if not config_path.parent.exists():
            raise HTTPException(
                status_code=400,
                detail=f"{body.client.capitalize()} is not installed on this system. "
                f"Please install {body.client.capitalize()} first.",
            )

        # Create parent directories if they don't exist
        config_path.parent.mkdir(parents=True, exist_ok=True)

        # Read existing config if it exists
        existing_config = {}
        if config_path.exists():
            try:
                with config_path.open("r") as f:
                    existing_config = json.load(f)
            except json.JSONDecodeError:
                # If file exists but is invalid JSON, start fresh
                existing_config = {"mcpServers": {}}

View on GitHub (pinned to 976ec789d2)

Solutions

1. Install the requested client application on the system, then retry.

When it happens

Trigger: Occurs when the requested MCP client application (e.g. Cursor, Claude) is not installed on the local system.

Common situations: See trigger scenarios.

AI-assisted analysis of langflow-ai/langflow@976ec789d2 (2026-08-14). Data as JSON: /api/errors/23c24ff2b1cb1492. Report an issue: GitHub.