In the shell: var t = db.max_time_ms; t.drop(); t.insert([{},{},{}]); t.getDB().adminCommand({configureFailPoint: "maxTimeAlwaysTimeOut" , mode: "off" }).ok; cursor = t.find({$where: function() { sleep(100); return true ; }}).maxTimeMS(100); // Returns error: { "$err" : "JavaScript execution terminated" , "code" : 16712 } // Turn on a fail point t.getDB().adminCommand({configureFailPoint: "maxTimeAlwaysTimeOut" , mode: "alwaysOn" }).ok; cursor = t.find({$where: function() { sleep(100); return true ; }}).maxTimeMS(100); // Returns error: { "$err" : "operation exceeded time limit" , "code" : 50 }