paperclipai/paperclip · error

This hostname is not allowed for this Paperclip instance. If

Error message

This hostname is not allowed for this Paperclip instance. If you want to allow a hostname, run npx paperclipai allowed-hostname <host>.

What it means

Error "This hostname is not allowed for this Paperclip instance. If you want to allow a hostname, run npx paperclipai allowed-hostname <host>." thrown in paperclipai/paperclip.

Source

Thrown at server/src/middleware/private-hostname-guard.ts:91

    if (!hostname) {
      const error = "Missing Host header. If you want to allow a hostname, run npx paperclipai allowed-hostname <host>.";
      if (wantsJson) {
        res.status(403).json({ error });
      } else {
        res.status(403).type("text/plain").send(error);
      }
      return;
    }

    if (isLoopbackHostname(hostname) || allowSet.has(hostname)) {
      next();
      return;
    }

    const error = BLOCKED_HOSTNAME_MESSAGE;
    if (wantsJson) {
      res.status(403).json({ error });
    } else {
      res.status(403).type("text/plain").send(error);
    }
  };
}

View on GitHub (pinned to 120ae5428f)

Solutions

1. Allow the hostname by running npx paperclipai allowed-hostname <host>, then retry.

When it happens

Trigger: Thrown at server/src/middleware/private-hostname-guard.ts:91 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of paperclipai/paperclip@120ae5428f (2026-08-18). Data as JSON: /api/errors/998446f5ff1d97ac. Report an issue: GitHub.