mongodb/node-mongodb-native · critical · MongoInvalidArgumentError

No AuthProvider for ${AuthMechanism.MONGODB_SCRAM_SHA256} de

Error message

No AuthProvider for ${AuthMechanism.MONGODB_SCRAM_SHA256} defined.

What it means

Thrown in prepareHandshakeDocument when the user's mechanism is the default 'MONGODB-CR' placeholder and the code attempts to pre-fetch the SCRAM-SHA-256 provider, but getOrCreateProvider returns undefined. The inline comment states 'This auth mechanism is always present', so reaching this throw means the default provider registry has been corrupted or overridden - this should never happen in a normal install.

Source

Thrown at src/cmap/connect.ts:266

    compression: compressors
  };

  if (options.loadBalanced === true) {
    handshakeDoc.loadBalanced = true;
  }

  const credentials = authContext.credentials;
  if (credentials) {
    if (credentials.mechanism === AuthMechanism.MONGODB_DEFAULT && credentials.username) {
      handshakeDoc.saslSupportedMechs = `${credentials.source}.${credentials.username}`;

      const provider = authContext.options.authProviders.getOrCreateProvider(
        AuthMechanism.MONGODB_SCRAM_SHA256,
        credentials.mechanismProperties
      );
      if (!provider) {
        // This auth mechanism is always present.
        throw new MongoInvalidArgumentError(
          `No AuthProvider for ${AuthMechanism.MONGODB_SCRAM_SHA256} defined.`
        );
      }
      return await provider.prepare(handshakeDoc, authContext);
    }
    const provider = authContext.options.authProviders.getOrCreateProvider(
      credentials.mechanism,
      credentials.mechanismProperties
    );
    if (!provider) {
      throw new MongoInvalidArgumentError(`No AuthProvider for ${credentials.mechanism} defined.`);
    }
    return await provider.prepare(handshakeDoc, authContext);
  }
  return handshakeDoc;
}

/**

View on GitHub (pinned to 3366c21a63)

Solutions

  1. Remove any custom authProviders option from MongoClientOptions so the default registry is used.
  2. Reinstall node_modules (rm -rf node_modules && npm install) to rule out a corrupted install.
  3. If using a bundler (webpack/esbuild), ensure the driver's auth provider modules are not tree-shaken or marked external incorrectly.
  4. Upgrade to a current driver release; if it persists, file a driver bug.

Example fix

// before
const client = new MongoClient(uri, { authProviders: customRegistryMissingScram });

// after
const client = new MongoClient(uri); // default registry always has SCRAM-SHA-256
Defensive patterns

Strategy: validation

Validate before calling

import { MongoClient, AuthMechanism } from 'mongodb';
// Smoke test that the default SCRAM-SHA-256 provider loads
function smokeTestProvider() {
  const c = new MongoClient('mongodb://u:p@localhost');
  const prov = c.options.authProviders?.getOrCreateProvider?.(AuthMechanism.MONGODB_SCRAM_SHA256);
  if (!prov) throw new Error('Driver install is missing the SCRAM-SHA-256 provider');
}

Type guard

function installIsHealthy(authProviders: any): boolean {
  return Boolean(authProviders?.getOrCreateProvider('SCRAM-SHA-256'));
}

Try / catch

import { MongoInvalidArgumentError } from 'mongodb';
try {
  await client.connect();
} catch (e) {
  if (e instanceof MongoInvalidArgumentError && /SCRAM-SHA-256/.test(e.message)) {
    // reinstall node_modules or remove custom authProviders override
  }
  throw e;
}

Prevention

When it happens

Trigger: Only when a custom authProviders was supplied to MongoClient that omits the SCRAM-SHA-256 provider, or the driver's module graph was tampered with such that the SCRAM-SHA-256 provider module failed to load. Fires in prepareHandshakeDocument (src/cmap/connect.ts:260-269) before the handshake is even sent.

Common situations: A custom authProviders option that filters out ScramSha256; a broken tree-shake/bundler configuration that dropped the default provider modules; a fork of the driver with the SCRAM provider registration removed; running against a corrupted node_modules.

Related errors

AI-assisted analysis of mongodb/node-mongodb-native@3366c21a63 (2026-08-04). Data as JSON: /data/errors/56f2ddd91a1d9e3f.json. Report an issue: GitHub.