mongodb/node-mongodb-native · error · MongoUnexpectedServerResponseError

Illegal profiling level value ${was}

Error message

Illegal profiling level value ${was}

What it means

Thrown by ProfilingLevelOperation.handleOk when the server's profile response reports a 'was' value that is not 0, 1, or 2. The driver maps 0->off, 1->slow_only, 2->all; any other value is unrecognized. It is a MongoUnexpectedServerResponseError, meaning the server returned data the driver cannot interpret - likely a newer/changed profiling scheme or an unusual server build.

Source

Thrown at src/operations/profiling_level.ts:41

    super(db, options);
    this.options = options;
  }

  override get commandName() {
    return 'profile' as const;
  }

  override buildCommandDocument(_connection: Connection): Document {
    return { profile: -1 };
  }

  override handleOk(response: InstanceType<typeof this.SERVER_COMMAND_RESPONSE_TYPE>): string {
    if (response.ok === 1) {
      const was = response.was;
      if (was === 0) return 'off';
      if (was === 1) return 'slow_only';
      if (was === 2) return 'all';
      throw new MongoUnexpectedServerResponseError(`Illegal profiling level value ${was}`);
    } else {
      throw new MongoUnexpectedServerResponseError('Error with profile command');
    }
  }
}

View on GitHub (pinned to 3366c21a63)

Solutions

1. Check the server version with db.admin().serverInfo() and compare against the driver's compatibility matrix; upgrade the driver if the server is newer.
2. Run the profile command directly (db.runCommand({ profile: -1 })) to inspect the raw 'was' value returned by your server.
3. If the value is genuinely new, file a driver issue so the mapping can be extended.
4. Pin to a server version whose profiling levels the driver understands while investigating.

try {
  const level = await db.getProfilingLevel();
} catch (e) {
  if (e instanceof MongoUnexpectedServerResponseError && /Illegal profiling/.test(e.message)) {
    // inspect raw value via db.runCommand({ profile: -1 }); possibly upgrade driver
  }
  throw e;
}

When it happens

Trigger: Calling db.getProfilingLevel() against a server that reports a profiling level outside the documented 0/1/2 set (e.g., a pre-release or fork build, or a future server version introducing new levels).

Common situations: Pointing the driver at a much newer server version that extended profiling levels; using a non-standard MongoDB-compatible build; driver version older than the server it is talking to.

Related errors

• Error with profile command
• Error with validation data
• Profiling level must be one of "${enumToString(ProfilingLeve
• Driver attempted to initialize in load balancing mode, but t
• Current topology does not support sessions

AI-assisted analysis of mongodb/node-mongodb-native@3366c21a63 (2026-08-04). Data as JSON: /data/errors/1a69910da1fa9c6b.json. Report an issue: GitHub.