mongodb/node-mongodb-native · error · MongoParseError

Cannot use srvMaxHosts or srvServiceName with a non-srv conn

Error message

Cannot use srvMaxHosts or srvServiceName with a non-srv connection string

What it means

Thrown in the non-SRV branch (connection_string.ts:486-498) when a plain mongodb:// URI is given but srvMaxHosts or srvServiceName appears in either the URI query string or the options object. These options only make sense for mongodb+srv:// URIs because they parameterize the SRV DNS lookup.

Source

Thrown at src/connection_string.ts:494

    if (mongoOptions.srvMaxHosts > 0 && typeof mongoOptions.replicaSet === 'string') {
      throw new MongoParseError('Cannot use srvMaxHosts option with replicaSet');
    }

    // SRV turns on TLS by default, but users can override and turn it off
    const noUserSpecifiedTLS = !objectOptions.has('tls') && !urlOptions.has('tls');
    const noUserSpecifiedSSL = !objectOptions.has('ssl') && !urlOptions.has('ssl');
    if (noUserSpecifiedTLS && noUserSpecifiedSSL) {
      mongoOptions.tls = true;
    }
  } else {
    const userSpecifiedSrvOptions =
      urlOptions.has('srvMaxHosts') ||
      objectOptions.has('srvMaxHosts') ||
      urlOptions.has('srvServiceName') ||
      objectOptions.has('srvServiceName');

    if (userSpecifiedSrvOptions) {
      throw new MongoParseError(
        'Cannot use srvMaxHosts or srvServiceName with a non-srv connection string'
      );
    }
  }

  if (mongoOptions.directConnection && mongoOptions.hosts.length !== 1) {
    throw new MongoParseError('directConnection option requires exactly one host');
  }

  if (
    !mongoOptions.proxyHost &&
    (mongoOptions.proxyPort || mongoOptions.proxyUsername || mongoOptions.proxyPassword)
  ) {
    throw new MongoParseError('Must specify proxyHost if other proxy options are passed');
  }

  if (
    (mongoOptions.proxyUsername && !mongoOptions.proxyPassword) ||

View on GitHub (pinned to 3366c21a63)

Solutions

1. Remove srvMaxHosts and srvServiceName from URI and options.
2. Or change the URI scheme to mongodb+srv:// if you genuinely want SRV resolution.

Example fix

// before
const c = new MongoClient('mongodb://host:27017/?srvMaxHosts=3');
// after
const c = new MongoClient('mongodb://host:27017/');
// or
const c = new MongoClient('mongodb+srv://cluster.example/?srvMaxHosts=3');

if (!uri.startsWith('mongodb+srv://')) {
  const params = new URL(uri).searchParams;
  if (params.has('srvMaxHosts') || params.has('srvServiceName') || 'srvMaxHosts' in opts || 'srvServiceName' in opts) {
    throw new Error('srvMaxHosts/srvServiceName require a mongodb+srv:// URI');
  }
}

When it happens

Trigger: URI like 'mongodb://host:27017/?srvMaxHosts=3' or new MongoClient('mongodb://host:27017/', { srvServiceName: 'customservice' }).

Common situations: Switching a URI from mongodb+srv:// to mongodb:// for testing or firewalls but leaving the SRV-only options in place; templated config that injects srv options unconditionally.

Related errors

• SRV URI does not support directConnection
• Option "srvHost" must not be empty
• No addresses found at host
• Multiple text records not allowed
• Text record may only set any of: ${VALID_TXT_RECORDS.join(',

AI-assisted analysis of mongodb/node-mongodb-native@3366c21a63 (2026-08-04). Data as JSON: /data/errors/f6c55f83fb5dbf71.json. Report an issue: GitHub.