mongodb/node-mongodb-native · error · MongoRuntimeError

Options for SrvPoller must exist and include srvHost

Error message

Options for SrvPoller must exist and include srvHost

What it means

Thrown by the SrvPoller constructor (src/sdam/srv_polling.ts:55) as MongoRuntimeError when the options object is missing or has no srvHost field. SrvPoller resolves hostnames for mongodb+srv:// connection strings by polling DNS SRV records; it requires a hostname to poll. This is an internal component constructed by the topology during SRV-based connection setup.

Solutions

1. Ensure the mongodb+srv:// URI has a valid hostname: mongodb+srv://cluster.example.net/dbname.
2. Verify DNS resolution of the SRV hostname works (nslookup or dig).
3. If the URI looks correct, report to driver maintainers as an internal error.

Example fix

// before
const client = new MongoClient('mongodb+srv:///test');
// after
const client = new MongoClient('mongodb+srv://cluster.example.net/test');

function assertSrvUri(uri) {
  if (uri.startsWith('mongodb+srv://')) {
    const host = uri.slice('mongodb+srv://'.length).split('/')[0];
    if (!host) throw new Error('mongodb+srv URI missing hostname');
  }
}

function hasSrvHost(uri): boolean {
  return /^mongodb\+srv:\/\/[^/]+/.test(uri);
}

try {
  await client.connect();
} catch (e) {
  if (e instanceof MongoRuntimeError && /srvHost/.test(e.message)) {
    // fix the URI to include a hostname
  }
  throw e;
}

When it happens

Trigger: Connecting with mongodb+srv:// but the parsed URI produced no srvHost (e.g. an empty or malformed SRV URI), or internal code constructing SrvPoller without options. Reached only on mongodb+srv:// connections.

Common situations: Malformed mongodb+srv:// URI missing the hostname (e.g. mongodb+srv:///dbname), corrupted URI parsing, or a driver bug.

Related errors

• Option "srvHost" must not be empty
• Cannot have empty URI params in DNS TXT Record
• Multiple text records not allowed
• No addresses found at host
• Server record does not have at least one more domain level…

AI-assisted analysis of mongodb/node-mongodb-native@dce7939f86 (2026-08-11). Data as JSON: /api/errors/f6e1adf34e8bcdcc. Report an issue: GitHub.

Appendix: source

Thrown at src/sdam/srv_polling.ts:55

export class SrvPoller extends TypedEventEmitter<SrvPollerEvents> {
  srvHost: string;
  rescanSrvIntervalMS: number;
  heartbeatFrequencyMS: number;
  haMode: boolean;
  generation: number;
  srvMaxHosts: number;
  srvServiceName: string;
  _timeout?: NodeJS.Timeout;

  /** @event */
  static readonly SRV_RECORD_DISCOVERY = 'srvRecordDiscovery' as const;

  constructor(options: SrvPollerOptions) {
    super();
    this.on('error', noop);

    if (!options || !options.srvHost) {
      throw new MongoRuntimeError('Options for SrvPoller must exist and include srvHost');
    }

    this.srvHost = options.srvHost;
    this.srvMaxHosts = options.srvMaxHosts ?? 0;
    this.srvServiceName = options.srvServiceName ?? 'mongodb';
    this.rescanSrvIntervalMS = 60000;
    this.heartbeatFrequencyMS = options.heartbeatFrequencyMS ?? 10000;

    this.haMode = false;
    this.generation = 0;

    this._timeout = undefined;
  }

  get srvAddress(): string {
    return `_${this.srvServiceName}._tcp.${this.srvHost}`;
  }

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