mantinedev/mantine · error · Error

Failed to fetch ${url}: ${response.status}

Error message

Failed to fetch ${url}: ${response.status}

What it means

The @mantine/mcp-server data client fetches JSON from a configured base URL with a timeout. When the HTTP response is not ok, it throws an error including the URL and status code. This is infrastructure-level: the MCP data server (Mantine docs data) is unreachable or erroring.

Source

Thrown at packages/@mantine/mcp-server/src/data-client.ts:35

  private readonly timeoutMs: number;
  private indexCache: IndexItem[] | null = null;
  private itemCache = new Map<string, ItemData>();

  constructor(baseUrl = 'https://mantine.dev/mcp', timeoutMs = 10000) {
    this.baseUrl = baseUrl.replace(/\/+$/, '');
    this.timeoutMs = timeoutMs;
  }

  private async fetchJson<T>(relativePath: string): Promise<T> {
    const controller = new AbortController();
    const timer = setTimeout(() => controller.abort(), this.timeoutMs);

    try {
      const url = `${this.baseUrl}/${relativePath.replace(/^\/+/, '')}`;
      const response = await fetch(url, { signal: controller.signal });

      if (!response.ok) {
        throw new Error(`Failed to fetch ${url}: ${response.status}`);
      }

      return (await response.json()) as T;
    } finally {
      clearTimeout(timer);
    }
  }

  async getIndex() {
    if (this.indexCache) {
      return this.indexCache;
    }

    this.indexCache = await this.fetchJson<IndexItem[]>('index.json');
    return this.indexCache;
  }

  async listItems(args: ListItemsArgs = {}) {

View on GitHub (pinned to 8a284e2c2c)

Solutions

1. Verify the base URL configuration points to a reachable host
2. Test connectivity directly: curl the URL from the same environment
3. Configure proxy/CA settings so Node's fetch can traverse the corporate network
4. Retry after transient failures or run the data source locally

Example fix

// before
new DataClient({ baseUrl: 'https://data.mantine.dev' }); // 500/404 from host

// after
// verify with curl, then point at a healthy mirror
new DataClient({ baseUrl: 'https://your-mirror.example.com' });

// Smoke-check reachability before starting the server
await fetch(`${baseUrl}/index.json`, { method: 'HEAD' }).catch(() => {
  console.error('MCP data host unreachable — check network/proxy');
});

try {
  const index = await client.getIndex();
} catch (e) {
  if (e instanceof Error && e.message.startsWith('Failed to fetch')) {
    // retry with backoff or switch baseUrl
  }
}

When it happens

Trigger: The MCP server cannot reach its data host (network blocked, proxy interference); base URL misconfigured; data endpoint returns 404/500; DNS or corporate firewall blocking the request.

Common situations: Running the MCP server behind a corporate proxy that strips requests; stale base URL after a data source migration; the remote data service being temporarily down; local offline development.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

• Request failed with status ${res.status}

AI-assisted analysis of mantinedev/mantine@8a284e2c2c (2026-08-28). Data as JSON: /api/errors/b2f08876730984df. Report an issue: GitHub.