I'm running my API method collecting everyday statistic simultaneously for 20 days (20 times):

	this.collection.aggregate(
		{
			$group: {
				_id: {
					"active": "$enable"
				},
				count: { $sum: 1 }
			}
		},
		{
			$project:{
				"active": "$_id.active",
				"_id": 0,
				"count": 1
			}
		}, callback);

During local tests on the workstation I got the next error every time after starting the application:
errmsg: 'not authorized on <servername> to execute command { aggregate: "tasks", pipeline: [ { $match: { createdTs:

, type:

} }, { $group: { _id:

, count:

} }, { $project:

} ] }'
Second and other calls to the API is always succeeded. Then I wait till the number of connections decreases from 5 (default pollSize) to the 2. After this I get this message again for a one time.

On the server I always have this message for a first time but I didn't find a relation between the error and the number of connections. Just after some delay in requests (3-5 mins) I get the error for a first time and the other requests are succeed.

This error is not appearing when I set poolSize: 1.

Could you tell me what is going wrong with this request or what information I should collect additionally to troubleshoot this error?

Thank you!