mongodb/node-mongodb-native · error · MongoAPIError

Option "srvHost" must not be empty

Error message

Option "srvHost" must not be empty

What it means

Thrown by resolveSRVRecord when options.srvHost is not a string. For mongodb+srv connection strings the driver must have a non-empty srvHost (the hostname portion) to perform DNS SRV/TXT lookups; a missing or non-string value is a configuration error and raises a MongoAPIError before any DNS query.

Solutions

1. Ensure the mongodb+srv URI has a non-empty hostname: mongodb+srv://cluster0.example.mongodb.net/dbname.
2. If constructing options manually, set srvHost to a valid hostname string.
3. Switch to a standard mongodb:// URI with explicit hosts if SRV is not required.
4. Validate the URI string before passing it to MongoClient.

Example fix

// before
const client = new MongoClient('mongodb+srv:///mydb');

// after
const client = new MongoClient('mongodb+srv://cluster0.example.mongodb.net/mydb');

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

function hasSrvHost(uri: string): boolean {
  if (!uri.startsWith('mongodb+srv://')) return true;
  const rest = uri.slice('mongodb+srv://'.length);
  const host = rest.split(/[/?]/)[0];
  return host.length > 0;
}

When it happens

Trigger: Fires at src/connection_string.ts:79 when `typeof options.srvHost !== 'string'`. Reachable whenever a mongodb+srv URI is used but internal option resolution produced a non-string srvHost, or when resolveSRVRecord is invoked with malformed options.

Common situations: Using a mongodb+srv URI whose host is empty (e.g. 'mongodb+srv:///dbname'); programmatically building options where srvHost was deleted/undefined; a connection-string parsing edge case; a bug in custom MongoClientOptions construction. For end users the URI itself is the usual culprit.

Related errors

• Options for SrvPoller must exist and include srvHost
• 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/36e22c514325014a. Report an issue: GitHub.

Appendix: source

Thrown at src/connection_string.ts:79

        throw firstDNSError;
      }
    }
  };
}

const resolveSrv = retryDNSTimeoutFor('SRV');
const resolveTxt = retryDNSTimeoutFor('TXT');

/**
 * Lookup a `mongodb+srv` connection string, combine the parts and reparse it as a normal
 * connection string.
 *
 * @param uri - The connection string to parse
 * @param options - Optional user provided connection string options
 */
export async function resolveSRVRecord(options: MongoOptions): Promise<HostAddress[]> {
  if (typeof options.srvHost !== 'string') {
    throw new MongoAPIError('Option "srvHost" must not be empty');
  }

  // Asynchronously start TXT resolution so that we do not have to wait until
  // the SRV record is resolved before starting a second DNS query.
  const lookupAddress = options.srvHost;
  const txtResolutionPromise = resolveTxt(lookupAddress);

  txtResolutionPromise.then(undefined, squashError); // rejections will be handled later

  const hostname = `_${options.srvServiceName}._tcp.${lookupAddress}`;
  // Resolve the SRV record and use the result as the list of hosts to connect to.
  const addresses = await resolveSrv(hostname);

  if (addresses.length === 0) {
    throw new MongoAPIError('No addresses found at host');
  }

  for (const { name } of addresses) {

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