unslothai/unsloth · error

Request failed (${status})

Error message

Request failed (${status})

What it means

Generic failure from mcpRequest, the shared wrapper for all /api/mcp/servers CRUD calls. After special-casing 204 (DELETE success with no body), it parses the JSON body and throws when !response.ok. parseErrorText prefers a FastAPI detail (formatted via formatFastApiDetail) or message field, and this listed fallback 'Request failed (status)' only appears when the error body is empty or unparseable.

Source

Thrown at studio/frontend/src/features/chat/api/mcp-servers-api.ts:52

    if (formatted) return formatted;
    if (typeof message === "string" && message) return message;
  }
  return `Request failed (${status})`;
}

async function mcpRequest<T>(
  path: string,
  init?: { method?: string; body?: object },
): Promise<T> {
  const response = await authFetch(`/api/mcp/servers${path}`, {
    method: init?.method,
    headers: init?.body ? { "Content-Type": "application/json" } : undefined,
    body: init?.body ? JSON.stringify(init.body) : undefined,
  });
  // 204 No Content (DELETE) has no body — calling .json() would throw.
  if (response.status === 204) return undefined as T;
  const json = await response.json().catch(() => null);
  if (!response.ok) throw new Error(parseErrorText(response.status, json));
  return json as T;
}

export function listMcpServers(): Promise<McpServerConfig[]> {
  return mcpRequest("/");
}

export function createMcpServer(payload: {
  displayName: string;
  url: string;
  headers?: Record<string, string>;
  isEnabled?: boolean;
  useOauth?: boolean;
}): Promise<McpServerConfig> {
  return mcpRequest("/", {
    method: "POST",
    body: {
      display_name: payload.displayName,

View on GitHub (pinned to 203007d190)

Solutions

1. Read the message: a real detail from the backend names the failing field or connection error; the bare 'Request failed (status)' fallback means the body was empty — check backend logs.
2. Validate the MCP server URL and headers before submitting.
3. Confirm the MCP server itself is reachable from the backend (not just from the browser).
4. Re-auth if status is 401/403.

// Validate before create
const url = new URL(payload.url); // throws on malformed URL
if (!/^https?:$/.test(url.protocol)) throw new Error('MCP server URL must be http(s)');

try { await createMcpServer(payload); }
catch (e) { showFormError(e.message); // message carries FastAPI detail when present }

When it happens

Trigger: listMcpServers ('/'), createMcpServer, update, delete, or health-check calls returning 4xx/5xx — e.g. invalid MCP server URL (422), duplicate server name, auth failure, or backend unable to reach the configured MCP server.

Common situations: Registering an MCP server with an unreachable/wrong URL; header schema violations; server-side MCP connection failures surfacing as 502; expired session.

Related errors

• family {getattr(fam, 'name', fam)!r} declares no prequant_fi
• lockfile not found: {path}
• load timed out (last progress: {prog})
• Unsupported diffusion memory_mode '{value}'. Use one of: {va
• Unsupported text_encoder_quant '{value}'. Use one of: {', '.

AI-assisted analysis of unslothai/unsloth@203007d190 (2026-08-15). Data as JSON: /api/errors/9a8220fb4d8f3efd. Report an issue: GitHub.